[JayG]

Originally Posted by JFP in PA

Yes, zinc is poisonous to catalytic converters, but the case for removing or lowering its content in engine oil is vastly overblown. By EPA law, the OEM manufacturer's are on the hook for the catalytic converters for 80,000 miles if they fail. So they lobbied the EPA to get zinc in the form of ZDDP reduced or even eliminated in engine oils on the basis that doing so would improve emissions by protecting the cats, and the EPA bought it. While it is easy to prove that the zinc kills the cats, the OEM's argument was purely a "straw man" to get out of having to pay for them if they crap out before 80K. If you watch how many cats actually fail early, you would see that not that many do, it is common to see cars in excess of 150K miles and the cats are fine. And of the cats that do fail, reports have noted that many of them failed because of gas additives, not zinc poisoning.

So we get saddled with low ZDDP oils, or oils with other metal salts replacing the ZDDP. Unfortunately, these alternative oil formulations do not demonstrate the same wear reduction characteristics that oils with high levels of ZDDP have, and often break down earlier, requiring shorter oil change intervals.

Based upon what we have seen, I prefer to stay with high ZDDP oils. ZDDP is very hard to beat for wear protection, I am yet to see anyone equal its performance with alternative compounds. And at the end of the day, the cats are a lot easier to replace than rebuilding or replacing an M96/97 engine.

that being the case, what are the oils with highest ZDDP?