Which octane should I use today for a GM 3.8 liter supercharged V6?

Question

Although the GM 3.8 liter supercharged V6 originally required the use of premium fuel,should I really use the premium,plus or regular for performance or saving of gas costs?

Answer 1

Yep, use the premium.

If you don't what will happen is that as the supercharger starts to come into play, the engine will start to "knock".

As you might know, knock is something that can kill an engine VERY quickly, SO panic not, the engine control module detects the knock and compensated by retarding your ignition. The knock then stops.

If you keep boosting further and harder, the engine may be retarded yet further to avoid knock. Only after you stop using so much boost will the control module start to tentatively bring the ignition back to normal.

The translation of all of that is your performance goes down the lavatory when under high boost - as does economy and performance in general until the engine has decided to put your ignition timing back to normal.

Someone else said you will run lean if you use regular - not so, partly because the o2 sensors would adjust and secondly because calorific value in fuel is NOT linked to octane - and indeed there is sometimes an INVERSE link. Methanol for example, has a very high octane rating - but has only (very roughly) half of the energy density.

In short, running on regular will NOT damage anything because the sensors will put your car into "safe running" - it will just trash your performance and your economy once the ignition start retarding.

Mark

Answer 2

you want to use premium, If you switch to regular, the computer will read it running as lean, and richen up the fuel trim, thus giving you significantly less mileage and preformance. Stick with High octane gas

Answer 3

it really doesn't matter but it is recommened not to use regular unleaded as it will run like a bag of **** and will eventually cause problems - take it from me, i had a VT supercharged V6 and i opted to "save" money. Because i wanted to save $4 a week using regular unleaded instead of premium, i stuffed up the car and had to fork out $800 to fix it......

Answer 4

Run what's recommended. it's what the computer is tuned for and what the car will perform best on. the savings of switching to regular will be eaten up in additional maintainance costs in short time.