Originally Posted By: Jeffs2006EvoIX
Its just that I feel that many folks consider a high zddp oil a better oil vs one that does not have as much in it. Example, SL vs SM etc.
Many niche oil companies like RP, Redline etc, exploit zddp as that "we wont comprimise engine wear to safe a catalitic converter". Could it just be possible that newer modern engines do not require so much zddp? hence the change?
Could it be that oil itself is just getting better produced? That the oil is the some of its "parts" that are just better than years back?
The vast majority of new engines don't require as much zddp because almost all new engines have roller follower valvetrains. The conversion to roller followers has been done since the mid-1980's mostly in pursuit of fuel economy. Then the EPA decided in the mid-90's to hold manufacturer's feet to the fire to warrant emissions control systems for 150,000 miles. This is where zddp levels in oil started to drop. Now SM oil controls Phosphorous in a range of 600-800ppm for -20 and -30 oils. -40 and -50 oils can still go up to 1000ppm. References I have read on other sites say that the anti-wear effects of zddp continue to increase up to about 1800ppm Phosphorous, then there can start to be a corrosive effect on some cam materials.
I believe that your Evo has a roller follower valvetrain, true? If so, then you shouldn't spend a lot of time worrying about cam wear. I have had 6 years of experience in developing roller follower valvetrains, comprising thousands of hours of testing and have never seen a total failure at the roller-cam interface. The trouble spot in a roller follower valvetrain is at the roller axle, where the needles continually pass over the same zone of the axle. And since you have put more aggressive cams and higher-load valve springs in your engine you have made the possibility for failure in this area higher.
I can't tell you with real test data the effect of varying levels of zddp on bearing axle life, but believe that more EP additive is better than less. (Since we develop valvetrains for OEM's, we are constrained to using 0W-20 and 5W-20 grades.) Out of the M1 family of oils, I would ask you to consider either 15W-50, which has 1200P, or TDT 5W-40, which has 1100P. Or Redline 5W-40 is a stout oil, but pricey and not available at your local WalMart. These are good oils for highly boosted engines.
Also, since you're racing your Evo, you don't still have cats on it, do you? So don't worry about high zddp content in your oil. If it were my engine, I would want the extra insurance against engine wear that zddp provides.
