I just switched to Brad Penn 20W50 (from Castrol GTX 10W30) that I picked up from LEN. It might be a bit early in the season to switch to 20W50, so I just want to make sure I don't make any mistakes running this oil in cold weather. I believe the minimum cold cranking temp for this weight is 32F. Is that correct? I flat tow the car to most events, I wouldn't crank it below 32F anyway, i'd be worried about freezing my butt off with no heat! Oil pressure obviously takes much longer to come down at idle, at cold start it's also a tad higher.

I filled it and took it out for a spin today. Oil temps got up to 185F, max after a good 20 minutes of driving. Head temps ran around 380F max, peak of 400F while flooring 5th around 3-4k rpm for 30+ seconds. I retarded timing across the board by 1-2 degrees to 30 degrees at WOT after 3000rpm, definitely helped keep head temps cooler. Before I hit 425F, probably almost dropped a valve seat and a load in my pants. Both test drives in 40-45 degree weather.

Not sure if this will help, Yarin, but I left my car hooked up to my Grand Cherokee overnight outside and both times that I towed it to Powertech it was way down in the 20's. 12 quarts of 20/50 and it started with no ill effects. Makes a helluva lot of racket though until it warms up enough to open the bypass! I thought about leaving it run to keep the oil warm while working at the autocross but my practical side got the best of me and I left the car home. Co drove with my brother in a car with nice heat instead!!

Drop your advance a few more degrees and rich up your mix a bit and your temps will drop. You're looking for the fine line of advance/AFR vs. temps/power and you're not there yet.

Yea, those head temps are a bit high. they s/b in the 325 to 350 max range. SPIKES to 400 are ok but not good.

Hey dom.. thanks for the input. u coming out to the meadowlands anytime soon? i'll be there tomorrow! 1st autox of the year..

I know I still have yet to find the ideal AFR/advance combo that yields ideal head temps. Right now i'm monitoring AFR on a single exhaust runner. I'll move it back to the collector before the muffler and see what I get. I fixed my exhaust today, shouldn't have any concern about air leaks upstream of the O2 any more.. Something is strange about my system, AFR jumps around a lot. No idea what the cause could be. Maybe its just tuning, maybe its an injector driver issue. i really dont know.

to be continued..