What type of oil do you use?

[Cudaah]

broke the engine in with conventional and then switched to mobil 1 10-30 recently just switched to 0-30 but may go back.

[Ck[FIN]]

I have used 10-40w conventional or 20w-50 pennzoil gt. My new 750hp small block uses 5w-40 fully synthetic.

[lemming303]

I switched to Royal Purple 5-30 in my 2004 f150. It has 95000 miles on it. I have bigger tires than stock on the truck and run an Edge programmer. The Royal Purple gives me about an extra mile per gallon.That's the difference between 13 and 14 mpg. I know that RP uses a lot of detergents in there oil and it really, really keeps your engine clean. We use RP in all of our equipment at work. I work in the oil field and we have high pressure, high volume pumps that can pump fluids at 20,000 PSI and 13 barrels a minute. Thats 546 gallons a minute. We also use it in planetary gear boxes and all our diesel engines.
I know there is a lot of detergents not only because they say it does, but we have to make sure and watch temperatures in the gear boxes to prevent foaming. That's in a 90 weight oil though, and were talking temps above 300 degrees. I know that doesn't have much to do with musclecars, but I'm just letting you know why I use RP. Sorry if I went off there.

[moper]

Depends on the engine. My normal stuff, 15-40 fleet grade from Car Quest...lol. (Valvoline)  Anything that matters, and customer engines with the meaty cams get Valvoline VR1, the straight racing 30 wt... It's I think #885 or soemthing like that. It aint cheap, but it works very well. A roller cam engine I'll run any 10-40.

[ViperMan]

Mobil 1 Full Synthetic 15w-50. Has a good rating for zinc and is only $23 at Wal-Mart for 5qts.

Yeup - that's what I run in my Stratus (different weight, though.)  110,000 miles and she still sings at high throttle.

Jeff