Oils with increased levels of ZDDP

Question:

In light of recent discussions in your Mechanic On Duty column regarding the reduction of the zinc additive ZDDP in many motor oils and the negative effect that could have on vintage engines, I thought this information from ConocoPhillips might be of interest. I believe that many Auto Restorer readers operating vintage automobiles and trucks would use motor oil with the specifications discussed if they knew that it was available.

Answer:

Thank you for taking the time to share this information with your fellow readers. Robert Stockwell, senior engineer for automotive products at ConocoPhillips Lubricants, stated that 76 High Performance Motor Oil SAE 20W-50 and Kendall GT-1 High Performance Motor Oil SAE 20W-50 have both been reformulated with an increased level of zinc dialkyldithiophosphate (ZDDP) for increased wear protection and oxidation resistance. These two oils now contain approximately 1200 ppm of zinc, which is actually more than what was in high performance motor oils back when our vintage cars were new.