Quote:
Originally Posted by rotorwrench
Anything more than 1200 ppm starts to become detrimental to the engine parts. This was where the API set the limits for good reason (for automobile engines). ZDDP has corrosive properties so don't get too carried away with it. Most diesel engines have larger & heavier duty parts than car engines so they did use higher amounts. The latest API CK-4 rating has reduced levels of ZDDP. Some of them are skirting the API CK-4 rating by listing the engine protection test results. They don't pass for that rating yet but if they eventually do then they won't have much more ZDDP than car engine oil has. They will just use other additives like they have for years. Diesel truck oil is overkill for most automobiles. The stuff helps with the high perfomance engines that started to show up in showrooms in 1958 but the earlier designs really would only need it for initial break in. After that, they would work just fine. The old flatheads don't need it at all. Rompum stompum engines with high compression and high lift, flat tappet cams will be the only ones that benefit from high ZDDP levels. Roller cams don't need high levels.
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I humbly disagree. My truck is a 71 stock 6cyl and PYB 10w-30 high mileage almost ruint my cam and did damage a lifter. I now have 15w-40 delo in it with an additive in it. I put the whole bottle in and I only needed 1/4 a bottle, but my engine runs real good on 5000+ppm of zddp. Wish I could get ahold of some old 30wt delo, but I may try some of that renagade 3000ppm oil or penn grade(brad penn). Now valvoline racing would be my last resort, but is an option. I just don't want to trust this epa mandated car oil anymore. Who wants to trust the government to protect their engines?