Hey all,

So I've always been putting premium in Cammy's 3.8L engine since I bought her in like 2006 - I just downloaded a pdf manual for her(she didn't come with hers) and it suggests putting in the basic gas...

So I guess is premium(like 91-93octane) worse for her than the cheap stuff, and should I switch over or just keep going with the expensive stuff.?

 

Premium won't hurt the car. The 3.8 is meant to run on basic, so anything higher than that is just an unneccessarily high expense.

I've found that mine runs best when I pump fuel with no ethanol in it. There's only one gas station in my town that has alcohol-free gas, and they've been getting my money for a while now. The alcohol tends to gunk up the engine and lower the gas mileage, etc...

 

regular gas will work fine, in my current lt1 im finding the car seems to run better with regular.

 

Good to know, will you allow me one more question?

I asked my friend, a young aspiring mechanic, the same question and he said I shouldn't change the type of gas because it might harm the engine since she's used to the premium.

Is he correct, or is it perfectly fine to make the change? I love my baby but damn money is getting harder and harder to come across nowadays.

 

The higher octane fuel helps with detonation delay -- important on performance engines and when you start doing some serious mods.

 

If everything is stock under the hood, I don't think you'll have a problem switching from premium to regular.

The engine can't really "get used to" a certain type of fuel. The fuel either explodes with enough force to run the engine, or it doesn't. The ECM/PCM is designed to get readings from various sensors and make adjustments based on everything, but it does that on-the-fly. It doesn't learn a fuel type and do only what it's supposed to for that type. It won't freak out if the gas type changes. It'll just compensate for the lower octane by adding a little less air.

If you've done any modding, it's probably best to stay with the premium. If your PCM has been tuned to a specific fuel type (factory tune is regular for the 3800), you should use that fuel type.

 

The higher octane gas is made to burn slower so it won't pre-ignite in higher compression engines,I'll run regular in anything that will burn it without "ping" or "dieseling".
The reason it's called dieseling when a gas motor knocks and tries to keep running after the ignition is shut off is because true diesel engines fire off compression heat without spark plugs and it's trying to do the same.
The ping you get from burning regular in a high compression gas engine is gas firing off from compression heat before the spark occurs hence being called pre-ignition,it's out of time and bad news which can cause engine damage.
If you have no ping or dieseling when changing to regular you will be fine regardless of what gas you have been running.
Regular gas is more volatile so you may even make better power and get better gas mileage,my '93 5.7 LT1 Z28 runs fine on it and I get awesome gas mileage.

 

Excellent, accurate post. A stock 3.8 will run fine on regular if it's in proper tune. End of story.

 

yeah. now i got my v6 and an old V8 heres what i know about my area. and gas.

oregon gas sucks its all E10 only and they passed a smog law keeping it E10 year round. not just winter for some states. in my 79 camaro i got a low compression 305 engine and i wont run anything lower than 91~92 in it. not because it will ping or knock on 87 but the 91 92 gas in my area is a little better quality than the bottom shelf 87 crap we get around here. now i can easily tune my timing on it to make use of it. im at like 14 degrees BDC with full manifold vac ect 35degree at 2500rpm. it can fire it earlier and bam i make good power and good MPG. (18~20 est)

the firebirds different though. the PCM OBDII crap is the problem with fuel changes. bone stock 87~92 is fine. the 3.8 without reprograming PCM our engines cant take advantage of the fact you can spark the fuel sooner with 92 which increases the combustion pressure and makes more power. (increased timing). there are some company's i forget who my other forum knows but there is a bone stock/ 92 tune you can get for your PCM that adjusts the timing range for the engine to LOVE 92 and take advantage of it.

so it wont hurt it but without actually being able to tune the engine to take advantage via timing, your not gaining anything out of running 92. my problem is alot of the gas around here is just BAD! it sits too long in the main tanks and its watery cause Ethanol attracts water. so its garbage here. thats why i use the 92 to compensate for it also back when that engine and car was around there wasnt E10 gas. if i could get unleaded 87 i would run that with the timing i got and it would be stronger than the 92. but im making due.

hope that helps some? sorry its long but theres some info there for yeah