MPG and Oil Brand
 

For my car's first oil change, I brought it to Toyota and they filled it with "Bulk" 0w20. I averaged about 29mpg over that time period. My car is a 2017 MT 86 with the 4.3 final drive ratio.

Recently, I changed my oil myself, being wary of what "bulk" meant (despite having a free change available) and went with a decent brand synthetic. (Schaeffer's 9000 0w20) Now I am averaging 35mpg over the last 1k miles.

While there are variables that may be contributing to the change like weather (I'm in the midwest) and driving habits varying. Can the oil really make that much of a difference in MPG? Also the car seems to idle a little better, maybe it's just in my head though.

Has anyone else had similar experiences? My car is mostly just an occasional driver for the weekends or days I don't take the train. I also haven't tracked my car or put any additional mods on it.

My take is weather and idle times. You're dumping fuel during a longer cold-start in colder months.

Toyota's 0w20 is reportedly some of the thinnest stock you can get, which should have great MPG's.

Though I've heard that high quality ester base (not sure what Shaeffer's uses) helps oil stick to metal and perhaps quiet it down which may have an effect on reducing friction.

I'd be surprised if you see a difference of 0.5 mpg between oil brands.

I'm figuring that your representative sample is too small and your experiment has a giant experimental error.

;)


humfrz

You're probably right, I need more test points!

if all variables are equal, same weight oil = same fuel consumption.

you would have to replicate this in a closed, controlled environment to get any meaningful test results.