Originally Posted By: tokyem
I don't know the pressure over rpm but let's say 60lbs at 5000rpm. Max temp is 240-250F. I have two oil coolers but ambient temps north of 100 are common. I don't expect to need cold starts below about 50F so can't imagine needing 5W or even 10w. Big concern is the life of the motor. And heat is my enemy.
I am not as focused on the weight as I am learning about additives. How much zinc is enough? Is Moly good or bad?
The single most important attribute of a motor oil is it's viscosity. Since you track your car understanding the oil pressure characteristics of your engine is the only way to make a proper oil selection and maximize engine life. In my experience the single biggest cause of engine failure at the track is due drivers not understanding and/or not paying attention to the engine OP.
60 psi at 5,000 rpm could be too low, it certainly would be for my 928. I'd suggest looking up the test spec's for your engine including the maximum system OP at by-pass.
Regarding ZDDP and Moly. 1,200-1,300 ppm of phosphorus I'm sure is more than enough and levels in excess of 1,600 ppm can be corrosive allowing pitting in some engines.
Moly is another common AW additive that work's with ZDDP.
The first number in an SAE grade (0W, 5W, 10W, 15W etc) tells one more than just the oils cold starting rating. Higher quality oils tend to have very good cold performance hence the reason the most advanced race oils are 0W and 5W oils.
Another oil to consider is M1 5W-50 as it is the only 50 grade oil on the Porsche A40 list.