Losing MPG after an oil change?

[nj0ywatch1np0rn]

My car now has 30K miles and changed my oil a total of 6x already. I used to think it was a fluke 4 changes later it happens. Using 5W-30 Mobil1 and OEM filter and I'll get 300mi when I normally get over 400mi on a full tank. Anyone had this happen as well?

[njerald]

My mileage is still the same at 26,000 miles.

Averaging 27.1+ mpg since new (50% city driving) with dino oil.

[CharmCityES]

my car has always averaged 27mpg
2003 4cyl w/ 59k
i also use mobil 1 5w30 and toyota filter

[smilepak]

V6 averages 22-24mpg on normal commute to and from work in LA Traffic

on long run w/o traffic averagefs 27mpg..

haven't been able to get beyond that.

[nj0ywatch1np0rn]

Sorry, i meant to add this is during the first couple of hundred miles after the oil change. It rebounds back to normal after awhile.

[TRD VVTi]

Your fuel mileage is a result of everything else, except the oil that you're using...

[workerant]

Originally Posted by nj0ywatch1np0rn

My car now has 30K miles and changed my oil a total of 6x already. I used to think it was a fluke 4 changes later it happens. Using 5W-30 Mobil1 and OEM filter and I'll get 300mi when I normally get over 400mi on a full tank. Anyone had this happen as well?

I do have a V6 SE '07 also and last 20k miles I use Mobile1 5W-20.. my next oil change (this weekend probably) I will use 5W-30. Anyway, my MPG is average around 28mpg. Using Toyota oil filter too.

My ODO is 40K.

[DressUpYourPet]

Its possible that your oil condition (dirty vs. clean), oil weight (5w30 vs 10w30) and type (synthetic or dino) would give you a mileage difference. However i think you'd need a lab and test instruments to measure it because the mpg change, if any, would be very small indeed. Other factors such as how much weight is in the car, engine state of tune, engine wear, dragging brakes, dirty throttle body, clogged air filter, or any combination of the above are far more likely to cause a decrease in mpg.

Unless your 5w30 oil is getting replaced with 90w gear oil or something equally ridiculous, something else is causing your mpg fluctuation.

[toyomoho]

Are you using different brand of gas? A blend with alcohol will cause a reduction in MPG.

Suggest you compute actually MPG then post back with your findings.

[phuangk]

7.5KM / Litre to 8.0KM / Litre here
that is around...
17.64 MPG to 18.81 MPG

I have 2008 4 Cyl Automatic
ODO right now is 3000KM (1864 Miles)
Half City and half highway driving.
Average daily driving to work is around 40KM (24.86 miles).
Hardly exceed more than 3000RPM when i step on the gas...
I hope this is because of the engin still new.

[nj0ywatch1np0rn]

so normally I would get 28MPG using Mobil1 5W-30. Never used anything else.
Usually the first tank or two of gas after the oil change, I get somewhere at 22-24MPG and eventually it will go back to the 28MPG. Same thing happens at every oil change!

It's not controlled but its consistent. Take the same route back and forth and don't go anywhere. If I need, I just use the spare car for small trips here-n-there.

I guess I'm the only one experiencing this problem haha.

[erie61]

Originally Posted by nj0ywatch1np0rn

My car now has 30K miles and changed my oil a total of 6x already. I used to think it was a fluke 4 changes later it happens. Using 5W-30 Mobil1 and OEM filter and I'll get 300mi when I normally get over 400mi on a full tank. Anyone had this happen as well?

I have a 2005 Camry, and have had the same problem. I also own a 1998 Camry which gets super mileage (42 mpg). Every time I have an oil change my mpg drops. It does come up somewhat a couple of weeks after. However, that means from 25 mpg, to approximately 27.7 mpg. I am seriously considering a trade in. With gas prices as they are, this is unacceptable.

[TRD VVTi]

A '98 Camry gets 42 MPG?

If that were the case, MANUFACTURERS would be buying them to figure out Toyotas secret...

[workerant]

Just did a fill up today.. and here is the latest info:
Price: $3.599
Gal Purchased: 12.631
Total Cost: $45.46
Odo: 41,141
Station: Texaco
Filled Tank (full): Yes
Previous tank MPG: 30.48

So my tank is only about 3/4 emptied when I fill up.
This Saturday I will do the oil change to 5w 30. I'll try to come back to let U know how my mpg affect.

[njerald]

Ho Hum...............