Mileage Drop - Oil Change?

[Oman]

There was a thread a while back about a mileage drop after getting an oil change in the FFH. Given that I have been keeping close track of the mileage I was getting the week before my first oil change and the mileage after. In my case over 95% of the mileage on the car is from the exact same route on a daily commute, so there is little variation in the route. The change was done at 5,200 miles - about 1/2 way to the first recommended change. I like to do the first one at 1/2 the normal interval. I used the dealer and made sure they used the proper weight synthetic.

 

My average for the 5 days commuting before the oil change was 36.6Mpg. The drive is 2/3 70Mph HWY and the rest 30-55Mph county roads.

 

My average for the 5 days after the oil change was 33.4Mpg.

 

There is however another factor that unfortunately clouds the validity of the oil change causing a drop in mileage -

 

An early cold spell hit here in Minnesota the day before the oil change! The car is kept in a heated garage during the night and it sits outside during the working day.

 

What I need is a bit of an Indian Summer for a week to see if it really was the oil change or the weather that has caused the mileage to drop.

 

Jon

[rfruth]

could too much oil cause this ?

[Oman]

The only thing I can think of is if the factory uses a different oil than they recommend for a change. Too much oil can cause foaming or other problems that are bad for other reasons, and I suppose could cause a drop in mileage. I have not checked the level myself yet (I had foot surgery and am hobbling around on crutches). I have heard that this engine drops in mileage if you use a standard oil vs. a synthetic. I'm not sure if I buy that. I'm guessing that it is the weather, but considering that it isn't THAT cold and I have not had to use the defrosters it seems to be a pretty big drop. In fact I'm not using the A/C which makes me think that the mileage should be a bit better that I had been getting overall because I used the A/C quite a bit.

 

Jon

 

 

could too much oil cause this ?

[mirak]

I really doubt it's the oil. The cold front you experienced in Minnesota hit the whole nation - to different degrees. Here in Wichita in the last week, temps dropped to the 40s during my morning and evening commutes, and my single-trip mpgs fell from the mid-40s to the mid-30s.

 

It's the cold.

[jeff_h]

It's the cold.

 

Ditto, you will not be alone in experiencing this, there will probably be a whole lotta "awwww now my MPG stinks" posts that will appear in here during the winter.

[kram1984]

Ditto, you will not be alone in experiencing this, there will probably be a whole lotta "awwww now my MPG stinks" posts that will appear in here during the winter.

 

Wow, I think you've found a silver-lining (albeit small in comparison to the negatives of the high temperatures the rest of the year) of living in SA Texas, where we're lucky to get 1-2 weeks where we even reach 32 F during the whole year.

[swsaint]

Ditto, you will not be alone in experiencing this, there will probably be a whole lotta "awwww now my MPG stinks" posts that will appear in here during the winter.

 

 

Yep, have already noticed my mileage on my daily commute has dropped from the 38 to 39 range to the 35 to 36 range since it has gotten colder here in Cleveland in the last week or so.

[jeff_h]

Wow, I think you've found a silver-lining (albeit small in comparison to the negatives of the high temperatures the rest of the year) of living in SA Texas, where we're lucky to get 1-2 weeks where we even reach 32 F during the whole year.

 

You don't get away unscathed, your MPG takes a hit when it gets really hot -- and y'all have plenty of that!