Oil change intervals - endless topic

[corncobs]

Our FFH's specify use of 5W-20 oil and your picture shows 5W-30 containers. :headscratch:

 

I hope you don't use that photo an an example of your doing it correctly when applying for warranty work on these cars.

Maybe that was just an 'example' photo from another vehicle, eh?

 

 

 

Looking at the pic I would guess it's acdii's former F150 which he traded in; look at the handle on the passenger a-pilar.

[acdii]

Yes thats the F150. I mean really, do you think the Fusion takes THAT much oil! :) Last I checked its just under 5 quarts, I have 6 sitting there. I let the dealer change the Hybrid oil, the truck was a $50 oil change if I let them do it.

[hybridbear]

On insurance policies, like warranties, the burden of proof typically falls on the consumer to prove that they did everything right, if they can't prove that they did everything right then the claim will be denied

 

I think you missed it. FORD, not you, has the burden of PROOF your changing the oil caused the failure. They can say whatever they want. They have to put there proof in writing. They can not reject a warranty claim because they say it did. As I said, an oil analysis will tell the type of oil and it's age. If it goes to the dealer 4 quarts low and has damage, it won't make a difference who changed the oil. The owner did not do the required oil level checks. If the oil filter failed? So what, it's a ford part. Could happen at the dealer, a certified non ford shop, or to you in the driveway.

 

Do what you want. I'm getting lazy, and the idea of taking the aerodynamic panel off will have me letting the dealer do it. But, they screw up also. So what would stop them from saying, "We changed the oil. You did not do the owner maintenance checks and that's why the motor failed", and voiding your warranty. No way for you to prove you did them. So you may want to take you car in every week and pay for the maintenance checks. That way you'll be covered. :)

 

And that's why this is called an endless topic. ;) :shift: :headspin:

[rico567]

<snip>

 

I agree and that is why I will never wait 10,000 miles to change oil. My Saab 9-3 had a sludge build up problem from the previous owner following Saab's direction to go 10,000 miles between oil changes. GM did this specifying full synthetic to try to make the Saabs seem lower maintenance, the problem was that most owners used regular oil and went 10,000+ miles between oil changes which led to sludge. I'd rather spend a little bit more often to change my oil every 5000 miles rather than have an issue later on.

 

10k on the odometer and 7.5k on the ICE would be a lot of highway driving. We got about 40% EV miles in the winter and are seeing 60-70% EV miles now that the weather is warm. That would mean that 5k on the odometer for me is less than 3k on the ICE. This is the interval I've chosen for now to change oil because of the cold starts and the effect that had on my Saab. It was fine for years but then I moved close to work where I was only driving 1.3 miles each way and the ICE never warmed up in the winter and after a few months of that, even with changing oil every 3k miles, I got enough sludge buildup that the oil pick up tube got blocked. Fortunately since I knew to watch for symptoms of this I did not do any damage to the engine but it was still a huge pain.

 

The SAAB is actually a case with a particular cause. We are currently driving an '04 SAAB 9-5 wagon with 150K miles on it, and I'm researching here only because we have no alternative but to replace the SAAB with another make, for reasons I'm sure you know. But we've owned at least one SAAB for the past 42 years, and if they were still in business, we'd be into another one without the slightest hesitation.

The "sludge monster" problem with the SAAB engines has a rather long and tedious history, but suffice it to say that the B245 engine ended up around 1998 having a PCV system that just wouldn't handle sludge buildup, due to redesigns of the engine itself, but not the PCV system. As you say, all would have been peachy if they had just stuck with moderate OCIs. All of our 9-5s have been changed every 5K with nothing but Mobil 1 0W-40, and nary a problem. The truth is that a lot of engines will give problems if fed a diet of dino oil and extended OCIs, but the SAAB engine in question, along with the notorious Toyota V-6, are textbook examples.

OTOH, will extended OCIs work in some cars? Absolutely, and the enormous number of used oil evaluations on BITOG demonstrates this. As you know, one must exercise reasonable judgement when changing oil, just like anything else. One may wish to "play it safe," and I'm old enough that it took me a while to educate myself about synthetic oils and break away from the oil changes every 3K, but the fact is that while a 10K OCI may seem like a lot, in Europe the manufacturer may spec >15K (25 or even 30K kilometers) for the same car.

Edited May 18, 2013 by rico567

[alpha754293]

Same here, my GT has clean oil, still almost full between changes of 5w-20w Mobil 1.

But, I changed it & filter early the first time and for the next several times, making sure the oil was clear.

It has 91k miles and the oil looks new when I change it.

 

For this FFH, I first changed the oil at 4k miles, actual mileage on the ICE was 2700 - the difference is that with all the Regen EV miles the ICE doesn't run that much compared to a normal ICE vehicle.

What bothers me is that many times the ICE is cold (or at the lower thermostat setting) when it starts and that is a sure-fire condition for carbon and sludge build up.

The Owner's Manual says to change oil at 10k miles on the odometer, meaning that the ICE is probably only running about 7500 real miles if you're trying to be a good hybrid driver.

Look at your tailpipe, I'll bet it shows a black residue from all the cold starts.

Full synthetic is good for 7500 or better, I'll change it at that mileage or so on the odometer, meaning the ICE has about 5000+ miles of operation.

Ford has their reasons, I have mine, however outmoded.

 

I have to get my tires rotated, I have 7400 miles now and been lazy.

 

I'm not entirely sure that you can do the calculation of ICE miles that easily.

 

I know that if I am driving on the highway and there's a slight grade or incline, that the electric motor would kick in to assist (although it doesn't really show up on the instantaneous fuel economy gauge or the tachometer either).

 

That calculation would ONLY be true if you're always on JUST ICE or JUST in EV(+) mode only but never a combination thereof; which I would think would be kinda hard to do safely. On a slight grade, you could be slowing down quite a LOT in order to try and stay in EV mode or that you'd have to push on the gas pedal a little harder to force it to switch over to ICE completely.

[acdii]

We need an hour meter that shows how long the ICE ran, and base oil change intervals on that.

[hybridbear]

The SAAB is actually a case with a particular cause. We are currently driving an '04 SAAB 9-5 wagon with 150K miles on it, and I'm researching here only because we have no alternative but to replace the SAAB with another make, for reasons I'm sure you know. But we've owned at least one SAAB for the past 42 years, and if they were still in business, we'd be into another one without the slightest hesitation.

The "sludge monster" problem with the SAAB engines has a rather long and tedious history, but suffice it to say that the B245 engine ended up around 1998 having a PCV system that just wouldn't handle sludge buildup, due to redesigns of the engine itself, but not the PCV system. As you say, all would have been peachy if they had just stuck with moderate OCIs. All of our 9-5s have been changed every 5K with nothing but Mobil 1 0W-40, and nary a problem. The truth is that a lot of engines will give problems if fed a diet of dino oil and extended OCIs, but the SAAB engine in question, along with the notorious Toyota V-6, are textbook examples.

OTOH, will extended OCIs work in some cars? Absolutely, and the enormous number of used oil evaluations on BITOG demonstrates this. As you know, one must exercise reasonable judgement when changing oil, just like anything else. One may wish to "play it safe," and I'm old enough that it took me a while to educate myself about synthetic oils and break away from the oil changes every 3K, but the fact is that while a 10K OCI may seem like a lot, in Europe the manufacturer may spec >15K (25 or even 30K kilometers) for the same car.

Exactly, I am inclined to "play it safe". I changed oil in my Saabs every 3k miles with conventional 5W-30 like the manual called for. A local Saab expert mechanic said that there is no benefit to using synthetic in the Saabs and that it is actually worse because the synthetic is thicker and that was an issue with the pickup screen getting clogged. But that is a Saab discussion, not a FFH discussion

 

I'm not entirely sure that you can do the calculation of ICE miles that easily.

 

I know that if I am driving on the highway and there's a slight grade or incline, that the electric motor would kick in to assist (although it doesn't really show up on the instantaneous fuel economy gauge or the tachometer either).

 

That calculation would ONLY be true if you're always on JUST ICE or JUST in EV(+) mode only but never a combination thereof; which I would think would be kinda hard to do safely. On a slight grade, you could be slowing down quite a LOT in order to try and stay in EV mode or that you'd have to push on the gas pedal a little harder to force it to switch over to ICE completely.

ICE miles are equal to odometer miles minus EV miles. Miles where the ICE is running with EV assist count as ICE miles because the ICE is running and contaminating the oil. Those miles are not EV miles because EV miles are measured as miles in EV only mode

[alpha754293]

ICE miles are equal to odometer miles minus EV miles. Miles where the ICE is running with EV assist count as ICE miles because the ICE is running and contaminating the oil. Those miles are not EV miles because EV miles are measured as miles in EV only mode

 

Yes, I know that. But the inherent problem with that calculation method basically says that if you count ICE+EV as ICE miles, then you are saying that the EV assist doesn't count towards the partial EV miles.

 

But that's not ENTIRELY true now is it? If say you're asking the powertrain/drivetrain system to deliver 100 kW of power, and 30% of it comes from the EV assist and you are driving like that for 0.1 miles, TECHNICALLY, the EV miles counter should be counted as/registering 30% of 0.1 miles (or 0.03 miles) while the ICE miles should be 70% of 0.1 miles or 0.07 miles.

 

It's a weighted function. If you were to discount the EV assist miles on the part of the EV system; you'll end up doing one of two things: Either a) you'll end up overpredicting the number of ICE miles (because now, in that example, you've since you're counting EV assist as ICE miles, you've overcalculated by 0.03 miles (30% or the percentage amount of the EV assist)) or b) you'll end up UNDERpredicting the number of EV miles because as far as the EV system is concerned, whether it's in pure EV mode or in EV assist mode, the electric motor is still working/running.

 

I hope you can see where I am going with this.

 

And there's also a HUGE distinction (based on the instrument cluster) because the IP cluster calls out specifically "EV miles" which I think is calculated ONLY for pure EV mode. But if you were to do the calculation (which honestly, shouldn't be THAT hard to do because the IP cluster already has to display it, so whether you want to calculate it based on time (and the integrate) or you just run multiple/separate timers/counters for anytime when the EV portion kicks in (so EV power != 0) and you do it as a weighted function - it really shouldn't be that hard to do.

 

I'm pretty sure that given the right know-how and the right tools, you can probably use a very basic laptop to do the data logging which then you can post-process afterwards to do the ACTUAL calculation. Or you get a bit of a more powerful laptop and you do the calculations on-the-fly.

 

(I actually thought about this very shortly after I had picked up my car). The upside to overpredicting the ICE miles - it forces people to change their oil more frequently/sooner. (Might only be a 1.01x factor, but still, it would still be more frequently/sooner than would actually be required.)

 

That was also a question that came up the moment that I started talking about maintanence and oil changes and stuff.

 

And on the assumption that the EV miles/EV system/EV mode requires ZERO maintenance (which might not ENTIRELY be true, but I haven't found any publically available documentation in regards to the EV maintenance stuff) - then once again - you're maintaining your ICE system sooner than is required. Doesn't hurt the car, but it hurts your wallet. A little. But if the EV system does require some very simple, basic, maintenance; then by NOT counting those EV assist miles as a weighted function towards the EV miles total; you might end up being late for the maintenance - which for the EV system, might not be such a good thing. The eCVT is the one thing that most immediately comes to mind when I think about what might require maintenance from the EV mode side. And checking the motor/generator (windings etc.) might also be a good check.

[acdii]

Methinks, you are overthinking it. Just follow the recommended change intervals in the manual based on your driving, and the engine will last as long as the car. The EV system does require maintenance based on time rather than miles. The cooling system needs to be flushed out every two years or so(haven't looked, basing on previous cars cooling cycles).

[alpha754293]

Methinks, you are overthinking it. Just follow the recommended change intervals in the manual based on your driving, and the engine will last as long as the car. The EV system does require maintenance based on time rather than miles. The cooling system needs to be flushed out every two years or so(haven't looked, basing on previous cars cooling cycles).

 

I have a habit of doing that. lol...

 

First coolant flush at 100,000 miles (160,000 km or 6 years) then every 50,000 miles (80,000 km or every 3 years). (Source: Owner's Manual, p. 434)

 

BTW...if it's solely based on mileage, then why would they recommend changing your oil every 3000 miles (5000 km) if you're going pretty much all stop-and-go traffic vs. 5000 miles (8000 km) if you do mostly highway?

 

So...I'd think that it DOES make a difference (as EV assist ought to put less of a load on the ICE than if it were ICE only). Just my thoughts...my $.02.

[acdii]

 

I have a habit of doing that. lol...

 

First coolant flush at 100,000 miles (160,000 km or 6 years) then every 50,000 miles (80,000 km or every 3 years). (Source: Owner's Manual, p. 434)

 

BTW...if it's solely based on mileage, then why would they recommend changing your oil every 3000 miles (5000 km) if you're going pretty much all stop-and-go traffic vs. 5000 miles (8000 km) if you do mostly highway?

 

So...I'd think that it DOES make a difference (as EV assist ought to put less of a load on the ICE than if it were ICE only). Just my thoughts...my $.02.

 

 

 

Constant speed vs load speeds. In City driving you put more load on the engine every time you accelerate. On the highway, the engine is under a much smaller load. When loaded more fuel is used, some of which is unburned (carbon)and blows past the rings, ending up in the oil. Same with towing, more load, even if on the highway, results in unburned fuel deposits in the oil.

 

The reasons for longer change intervals now is partially due to better filtration, and partially due to better additives in the oils that allow them to carry the deposits to the filter where they can get filtered out, and the additives also last much longer so the engine stays cleaner. The oil does 3 things, first and foremost, provides lubrication, second it acts as a cooler, and third holds deposits in suspension so they can be filtered out.

 

What kills oil, heat is the #1 killer, and with a managed cooling system like we have in cars now, thats no longer as critical as it used to be. Engines run cooler(gee ask ME how I know!), so the oil lasts longer. Heat turns oil to sludge, and that is the biggest killer of engines. It clogs drain holes, plugs up galleys, and gums up the works causing the engine to run hotter, causing even more sludge until eventually engine failure.

 

Dirt is the second thing that kills oil, so a good filter is a must. Third, oil does eventually wear out, not the actual oil itself, but the additives suspended in the oil. If you ever saw a Blackstone report, it lists the various additives in the oil and percentage of what it has left. It contains metals and minerals that protect metal parts, and other ingredients that attract deposits.

 

If you really want to get deep down and dirty about oil, I suggest sending 2 samples to Blackstone for analysis, one sample fresh unused oil that you put in, and one after 10K miles and then compare the results. It will show you exactly which components are used up, and how much contamination is in the oil.

 

 

EDIT: I think that I will do this on both my cars at the first oil change, or maybe when I get the new Fusion, pull some oil and send it in, then another sample at the first change. Too late on the Flex, so it will have to start with the first change.

Edited May 21, 2013 by acdii

[alpha754293]

 

Constant speed vs load speeds. In City driving you put more load on the engine every time you accelerate. On the highway, the engine is under a much smaller load. When loaded more fuel is used, some of which is unburned (carbon)and blows past the rings, ending up in the oil. Same with towing, more load, even if on the highway, results in unburned fuel deposits in the oil.

 

EDIT: I think that I will do this on both my cars at the first oil change, or maybe when I get the new Fusion, pull some oil and send it in, then another sample at the first change. Too late on the Flex, so it will have to start with the first change.

 

 

I know. I was just kidding. lol..

 

There are a lot of things that has made the longer oil changes possible. Engine manufacturing, better tolerances, better filtration, better oil production, etc. etc. etc. all play a role.

[alpha754293]

We need an hour meter that shows how long the ICE ran, and base oil change intervals on that.

 

Like I said, I don't think that it's THAT hard to do since the info is already used to drive the cluster.

 

Even if you had a dummy system that was optics based (slower, less precise), it's still possible to do it.

 

(Course, tapping into the engine/trip computers would be the better way of doing it, but...mehhh...or in my case, I just ask the respective engineers how to do it/what I need to do.) ;)

 

Wow...I am SUCH a geek. lol...and if I actually did that, I have WAYYY too much time on my hands. :):):)

[acdii]

Maybe it can be done with the scangaugeii? Should write them and see if it can record engine running hours,

[dalesky]

I would think that Ford engineers took into consideration the fact that their 10,000 mile oil change recomendation is appropriate for an engine that does not run all the time like a normal internal combustion car engine. don't you think?

Also, I know that synthetic oil is very long lasting, and am not worried about what seems like a long interval. Heck, on a high performance engine I have seen 7500 mi change dates. Car restorers I know, who drop in some big block stuff also aren't afraid to go 10,000 mi.

Just had to add my 2 pennies worth to this endless topic!

[hybridbear]

Fascinating comments alpha & acdii! :)

 

I'm inclined to stick with changing my oil approximately every 3000 ICE miles regardless of the percentage of oil life the dash displays. This is probably some overkill but it's cheap insurance.

 

It's a very interesting discussion that you mention about the load under EV Assist as meaning you could go longer between oil changes. The issue I think with taking it to this detail is that you don't do that with any other ICE only car saying that since you did a little bit of heavy acceleration, etc

[acdii]

Oil change interval on my F150 and Flex EB are both 10K miles. I used to go 9500 miles between changes on my F350 7.3 Powerstroke and could have gone 12K on it.

[alpha754293]

I would think that Ford engineers took into consideration the fact that their 10,000 mile oil change recomendation is appropriate for an engine that does not run all the time like a normal internal combustion car engine. don't you think?

Also, I know that synthetic oil is very long lasting, and am not worried about what seems like a long interval. Heck, on a high performance engine I have seen 7500 mi change dates. Car restorers I know, who drop in some big block stuff also aren't afraid to go 10,000 mi.

Just had to add my 2 pennies worth to this endless topic!

 

Well...generally, owner's manual is written for like the "middle-of-the-pack" type. So sorta yes and no. The big question then becomes what IS or what MAKES the "middle-of-the-pack"? There are better, more advanced ways of telling, but the reality is that the vast majority of people lack the physical and sometimes mental tools to do that, so the number that's published is a kinda good "rule-of-thumb" type number. (The real answer should be "it depends") but that doesn't really hold up in court and isn't helpful for people who are not technically inclined.

 

And usually, such numbers are also quite conservative too. And that might be done to protect against legal liability/warranty.

 

Fascinating comments alpha & acdii! :)

 

I'm inclined to stick with changing my oil approximately every 3000 ICE miles regardless of the percentage of oil life the dash displays. This is probably some overkill but it's cheap insurance.

 

It's a very interesting discussion that you mention about the load under EV Assist as meaning you could go longer between oil changes. The issue I think with taking it to this detail is that you don't do that with any other ICE only car saying that since you did a little bit of heavy acceleration, etc

 

In the words of one of my engine profs: "there's no such thing as changing your oil too often. It only hurts your wallet."

 

Well...let me put it to you this way - suppose that there's a consumable product in the oil. I dunno. Let's call it X. (Not going to really get into a discussion about what X is cuz I'm not a chemical engineer).

 

And suppose that you start off with 100 units of X. Now suppose that if you accerate hard, you consume 1 unit of X. We're talking like wide open throttle (WOT) acceleration. If you push on the gas pedal 50%, you use 0.5 units of X. If you only push on your gas pedal 10%, you use 0.1 units of X. And it's measured say....from each time you take off from a red light or stop sign.

 

So each time you do it, it'll subtract that amount from the 100 units total. If you floor it from a light, you'll end up with 99 units left. If you only push on the gas pedal 10% from the light, you'll end up with 99.9 units left. And you drive and drive and drive until you hit 0 units of X and you have to replace it with an oil change.

 

THAT would be a MUCH better indicator as to when you should need to change your oil than by power-on hours (POH) or miles. Suppose that each time you push on the gas pedal, you automatically travel 1 mile. That means that if you constantly are flooring it, you have to change it after 100 miles. If you push on the gas pedal only 10%, you don't have to change it for 1000 miles.

 

That would be the ideal method of measuring and determine when oil changes needs to occur. The problem is that the correlation between oil wear and how someone drives (load) isn't well characterized. In fact, I'm not sure if it's characterized at all.

 

I say this because to your point about normal ICE under normal acceleration vs. heavy acceleration vs. having EV assist - that would be the difference. If there's a way to correlate how someone drives, by the engine load vs. oil life, that would ultimately be the best. But, since it can't be done like that yet - miles is the substitute. Not a very good one (cuz it's a kind of one-size-fits-all approach) but for the most part, it's worked generally reasonably well over the past oh I dunno how many years.

 

And I said that I wasn't going to talk much about what the X is because it gets into the discussion about finding something that you can put as an additive to the oil without affecting its performance (which is impossible or nearly impossible) but is consumed at some rate as a function of engine load and ALMOST (nearly) based on nothing else. (You can kinda bake in the effects of temperature and pressure into the engine load equation).

 

At a broad/upper level way of looking at it - it is really just a MUCH MORE detailed version of the whole weighted function idea. Only that my x_i (x subscript i) is the rate of consumption rather than how many miles is driven contributed by the two systems: ICE and EV.

 

And sometimes, it's hard enough getting people to put gas when they're supposed to/when they need to. I can just picture people seizing their engines because they forget to put oil in or take the car in for an oil change. *rolls eyes*...

[acdii]

Easiest and best method to determine WHEN you should change the oil. http://www.blackstone-labs.com/ Easy, simple, and good for record keeping. I used this when I drove the F350 since an oil change on that beast was well over $50 and that was back in 2003. Learned I could go 12K miles between oil changes, so I had a buffer zone as I usually ran 9500 between changes.

 

There is some good reading there too regarding TBN, which is what alpha is referring to in his post. After about 4-5 samples are done, you will have a very good idea on just when you should change out your oil. It also gives you a very good idea on what condition your engine is in, especially if you buy a used car and hove no idea of what kind of maintenance was performed on it, or how hard it was driven. One other thing it will tell you is how well your air filter is doing, high silicon levels can show how much dirt makes it past the air filter. This is especially useful for turbocharged applications as dirt making it past a filter(K&N are notorious for this) can "dust" a turbine and wear it down to nibs and make it useless. There are variations to consider though since Silicon can also be high from gasket materials in a new engine. It also tells you how well the engine is performing or if you have a potential problem. If fuel is detected it is an indication of a rich condition, leaking injector, etc. Too many particulates in a diesel is an indication of too much fuel being injected. It also detect water or antifreeze, both are bad things to have show up as you have a leak in one of the internal gaskets, or worse a crack.

Edited May 22, 2013 by acdii

[neod192]

So here's a question from someone who's not a mechanic :) What does the oil life indicator in the car measure and can it be used to determine when the oil should be changed? Is it when it gets to a certain percentage: 40, 30, 20?

 

At a minimum, I'm going to change mine once a year, but what if I drive 8k miles and the oil life indicator is down to 5%?

Edited May 22, 2013 by neod192

[acdii]

Based on mileage on most cars, some have an actual device in the oil pan that measures something in the oil to determine its change interval. The one in the car is set to 10,000 miles and can be adjusted to other mile warnings. When it reaches about 10% it will fire off warnings on the dash, then when it hits 0, it says Change Oil Now.

[alpha754293]

Easiest and best method to determine WHEN you should change the oil. http://www.blackstone-labs.com/ Easy, simple, and good for record keeping. I used this when I drove the F350 since an oil change on that beast was well over $50 and that was back in 2003. Learned I could go 12K miles between oil changes, so I had a buffer zone as I usually ran 9500 between changes.

 

Will they be able to differentiate between an Otto-cycle ICE and an Atkinson cycle of the FFH? I'm assuming that the calibration will need to be changed for their chemical analysis (since different thermodynamic cycle would mean that the properties of combustion have changed, which means that your combustion chemistry has changed (somewhat, however slightly). And if they're measuring or basing their conclusions in their reports from samples taken at the ppm or ppb levels, then I would think that the calibration of the analysis equipment is VERY sensitive to the type of thermodynamic cycle your engine is running, right?

[acdii]

They record your vehicle, so assume they have a database on different engine types. They do differentiate between gas and diesel on the analysis so they can perform the correct tests. Wont know until its done though. You can ask them on their web page, they do respond back fairly quickly too.

[rico567]

Read and heed what "acdii" says!

 

The only (ONLY) way to determine an oil's condition in a particular engine is a UOA (Used Oil Analysis). I did one on my truck after its mileage dropped to about 2K per year and I decided to leave the oil in there a full year. The Blackstone Labs report came back that the oil was fine and I could then quit worrying about it. Go to whatever OCI you feel comfortable with, then take a sample (the kit is free from Blackstone) and test it. Chances are, they will come back and say that your oil is doing fine, and they may even recommend that you go a longer interval and test again.

 

It's useless to speculate about this, or rely on information about other people's vehicles. Even if they have the same car, chances are they don't drive the same way.

[alpha754293]

They record your vehicle, so assume they have a database on different engine types. They do differentiate between gas and diesel on the analysis so they can perform the correct tests. Wont know until its done though. You can ask them on their web page, they do respond back fairly quickly too.

 

Hybrids (FFH for example) are still VERY new.

 

When the first Prius (technically second gen from Toyota's perspective) came over to NA in 1997/'98, they weren't really sure HOW long the battery was going to last so they programmed the battery gauge to be super conservative so that 0% SoC(gauge) was actually 40% SoC (actual) (and 100% (gauge) was 60% actual.)

 

We have a better idea now, but I have a feeling that given the recent brou ha ha re: Consumer Reports v. EPA (Kia/Hyundai/Ford by extension) - I think that all of the parties agree that there needs to be a change in the test and thereby the calibration for hybrid vehicles. But to the detriment of Consumer Reports, they sell more magazines claiming that a car maker is wrong than a car-maker is half-right. *rolls eyes*....*sigh*...*

 

So I would think that the calibration would be very hard to determine/set if you can't figure out the chemical reaction rate that you're looking for and relating it back to the infinite variability of how people drive.