Found this in another forum. Does anyone think the API limits of ZDDP are to low to produce oils of optimal performance?
quote:[ September 13, 2003, 11:00 PM: Message edited by: buster ]
When the oil companies switched from SH to SJ class oils, they reduced the amount of ZDDP in their formulas. This stuff (ZDDP) can harm catalytic converters over time and the EPA was pressuring the automakers to increase the warranty on their emissions equipment from 50,000 to 100,000 miles. Mobil 1 went further in reducing this compound than any other oil I know of, dropping their level to 0.075% while most SH & SJ oils have been 0.10% to 0.15% and racing formulations could have 0.20% or more. I think that Mobil 1 over-estimated the protective benefits of their Tri-Synthetic formula base oil, when they went the extremely low ZDDP additive route and the result is a lower than anticipated level of protection in real world conditions. Nothing catastrophic, but lower protection nonetheless.% zinc is the amount of zinc used as an extreme pressure, anti-wear additive. The zinc is only used when there is actual metal to metal contact in the engine. Hopefully the oil will do its job and this will rarely occur, but if it does, the zinc compounds react with the metal to prevent scuffing and wear. A level of 0.11% is enough to protect an automobile engine for the extended oil drain interval, under normal use. Those of you with high revving, air cooled motorcycles or turbo charged cars or bikes might want to look at the oils with the higher zinc content. More does not give you better protection, it gives you longer protection , if the rate of metal to metal contact is abnormally high. High zinc content can lead to deposit formation and plug fouling.... That zinc quote is from the Hackett article? I think he underestimates the usefulness of zinc in our engines. Actually, he recommends .11% zinc for the AVERAGE motorist. More if you have a high-performance, rev-happy engine. The SL class of oils have only .10% zinc and the older Mobil 1 Tri-Synthetic formula had a meager 0.075%. The amount of zinc phosphate required to cause trouble is .20% or higher and even among the highest-performance oils available today, you will have trouble find anything over .15%. Amsoil is probably the highest of all the well-known oils made today but Amsoil claims that if the base oil's volatility is low (single digits as theirs is), the amount of ZDDP which will be passing through the emissions and exhaust systems will be low and not likely to cause trouble. Question: about the levels of zinc...all oil has around .1%. Amsoil has .5%. 11 out of 12 oil manufactures run about .1% zinc. Amsoil is the only one that runs more.