I have a '99 3.8 that I built. I have .030" over pistons, and a higher lift cam which produce more compression. More compression needs more octane. So, I use plus '89 Amoco fuels only. Works fine for me, but without built engine, I suggest just plan ol regular.

 

I use mid garde, but not nessacarly for permence. Some premium fuels put in great additives and work pretty well. all midgrade is is 1/3 premium. so I just use that to get a good octane & still get the good stuff. btw, i believe shell V-power is the best and always get shell.

 

speedway man...

 

third stupidest thing ive ever herd in my life *** gass come on

 

lmao, i mostly use shell or chevron premium, but since gas has gone up shell is the most expensive so i might just use chevrom\n

 

the only way ure gonna get any power outta a higher octane gas is if ure car is tuned for it.. if not then ure really jus wastin ure money in the higher grade gas

 

i use 93, but my car is tuned for it, and the only way you can tell is if you are tuned, and or bulit

 

I use regular in mine.....works fine for me.

 

I used 94 , racing gas , E-85 all day long, just playing

 

It may just be me but i have a 3.8 i havent noticed a difference in power or anything but i think with md-grade i get better gas mileage. I use both. I normally use regular but ill fill up with regular 2 times the third time i use midgrade. It helps to keep the injectors clean.