is mixing different types of gas bad for t fillhe car??
 

Hey guys just a quick question.
ive downed about 4000 miles on my car so far and read higher octane *could* help with my cricket noise a bit, as well as being betterfor the car and such.

ive recently gone from the east coast 92 wawa e10 gas to a 93shell. however much to my dismay, my mileage actually went down

i wasnt driving rougher, if anything i drove as careful as possible during my first fill in for shell.

im now thinking of trying out sunoco (shell, wawa, and sunoco are pretty abundant in my area of delaware/pa) should i do anything before fillin her up? is there such a thing as flushing out the car completely of the fluids and starting up fresh?? id like to switch my engine oils and trasmission fluids to motul eventually so i thought id ask ahead of time! :thanks:

also, if anyones a local... wawa vs sunoco vs shell, which do you use??

For mpg comparison purposes, you MUST be driving with the same driving style, and almost the same, if not identical, mix of highway/street usage. Otherwise, the mpg comparison is useless because you have too many variables.

precisely ! my driving style was id say about 75% more careful then normal,( never shifted above 4k rev) and i was averaging 30.5 on average before on 92 wawa. then i dropped to 28mpg on my first fillup on shell while i drove in the same conditions, but safer so im a bit appalled....

Hmm, you might want to keep on the Shell for a couple more tanks, because a sample size of 1 is not enough. Instead of trying to drive carefully, just try driving like before. Change one thing at a time, so you can analyze the change effectively.

I'd just use up/drain out the old gas/fluids and fill with the new gas/fluids.



humfrz

You should try a few tanks before making a clear decision.
There's so many variables...
Was the batch of gas you got not quite the octane it said? Was it hotter/colder out? Was the car idling longer? did you put the new type of gas in when there was still a large volume of fuel left?


I use Shell 91 (highest octane I can get) and I don't put anything else in unless I absolutely need to.

I would repaint

You can't even compare Wawa fuel because they get their fuel from the cheapest place possible. It's never consistent. Also, Wawa does not add any additives to the fuel. The only reason Wawa has fuel is to bring customers into the stores. They don't make a dime on fuel. Stay with a quality fuel like v power from shell.

Recommended is 94, some places don't sell that so don't use anything under 91 or "Premium". It's okay to mix. Second, there's a warning in the owner's manual to not use any gas with a % of ethanol. Can't remember the number but it says try to stay away from ethanol gas.

I buy at the Shell at the intersection of Thompson Station and Paper Mill Rd across from the Bank of America. I get the 93 and have not noticed any difference but don't have many miles on the car yet.

They don't have the very best prices but it still beats Pa gas stations, and they have a lot of traffic in and out so thetanks get refilled often.

91 is "good enough" but 93 will get you more power, better mpg, and safer with less knock. If you have it available it's worth the extra money. Mixing different company's gas is not bad.

In Florida it goes from 87, 89, to 93 so I just use 93 becuase they do not have the 91 octane that it recommends. When I was low on cash I did mix half 89 and half 93 and it should be good.

The manual reccommends 93 octane...stop