VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc zddp in motor oil

i have been reading about the lack of an additive called zddp in modern motor oils. i have noted a recent ad in g & d selling motorhead motor oil which supposedly still has the necessary zddp. i have three pre 1951 cars which i drive less than 1000 miles a year. the articles i read indicate the lack of zddp can eat up a camshaft in just a few hundred miles. i am curious of whether this is a real concern and if so what is the best way to deal with it. some of the articles i have read are from camshaft manufacturers while others are from companies promoting a product. if you want to see the amount of material out there do a search on zddp motor oil. david

The new oils rated for service SM have a REDUCED amount of ZINC. They will be sufficent for your older engines. The stories arose when new cam shafts (of poor quality) wore out in a short time. The cam to lifter pressure is very "light" in your 6 cylinder engines and there is nothing to worry about. These engines ran for 100,000 miles with no cam problems-with the almost no-zinc oil available 50 years ago.

From what I've read I believe Gene is correct. The problem arose with some of the Asian sourced camshafts that had questionable metallurgy. If you have the original cam you should be ok with just about any modern oil. Some of the internet discussions suggest using Shell Rotella oil (diesel spec) as it has the zddp additive, yet I just heard recently that Shell is reducing the amount of additive in their oils.

exon HD 30 is an oil formulated for diesel engines and it still contains adequate amounts of the Zinc addative. i buy it in 55 gal drums from the local exon distributor. its available in qts and gals. mike

Shell Rotella Diesel oil is often mentioned but any 15W-40 Diesel grade oil had more Zinc at one time. If it has the higher amount of Zinc it will be rated for service SL (SM shold not be mentioned)....Even the later diesel oils have had the zinc reduced. Look for bottles of SL rated oils in the less popular grades, like #30, 10W-40, and you will still find iit in 15W-40 as it also can be a "slow seller" in parts stores.
The GM Engine Oil Supplement, which had a high zinc content and intended for new camshaft break-in has also been discontinued from what I have read.
It still boils down to the reduced zinc oil is OK for "uesd" camshafts, older cars and non-high performance engines. If you change the oil every 1000 moles or once a year there will never be a problem.