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Has zinc been removed from motor oils?

“I am having thrust bearing failure in a 4.6 modified performance engine. This is a street/strip engine. Many of my friends are having the same problem. I think it is the result of the removal of zinc from the oil. I was told by two separate racing engine builders that the EPA ordered the removal of the zinc from over-the-counter motor oil. I use Mobil 1™ 5W-20. Is this true and do you think a zinc additive might help?”

Randy Lovejoy, Americas, Georgia

Answer

The active ingredient that you are talking about is phosphorus that is added through a component called ZDDP. For products that meet the ILSAC GF-5 specification, the phosphorus levels for the oil must be less than 800 ppm phosphorus. The ILSAC level for phosphorus has been reduced to protect the catalytic converter and other emission protection equipment. The engine manufacturers are confident that this level of phosphorus will protect both new and older engines. However, there are Mobil 1™ synthetic oils that have a higher level of phosphorus (phos) and can be used in engines in racing or high-performance applications; see the attached table.

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