For those of us that own older and performance vehicles, it is always nerve-racking to buy engine oil. Why? Because we fear that the reduced levels of zinc and  phosphorus will  not properly  protect the engine. This is particularly true for old cars with solid lifters trying to break in a new camshaft. For my old Rambler, I would buy oil designed for Diesels and off-highway vehicles because of the high levels of zinc and phosphrous. Mobil Oil has answered the question that has been on the minds of a lot of hot rodders.

Question:
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, GA
Answer:
The active ingredient that you are talking about is phosphorus which is added thru a component called ZDDP. For products that meet the new ILSAC GF-4 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 a...