[EldoFan]

With regards to the 4.9L V8 that was a Cadillac mainstay up until the N* really took over, I was wondering something.........I read here (scroll to bottom) that the recommended fuel for it is 'premium unleaded'. Is that true?? And if so.....what would be the risks one would take if he used regular??

 

[vsd]

I don't know if it's true, but the consequence of running regular fuel in a high compression engine, is that you would get knock, which is harmful to the engine. My Lexus requires 91 octane, but I can get away with running 89 in it w/o knocking if I don't run it hard, but I don't like to do it often because you never know when you'll need to hit the gas, and I don't wanna blow the engine over that. If the engine is never, it should have a knock sensor that will retard the timing if you use a lower grade gas, it will keep the engine safe, but will sacrifice performance.