Bob Olree at the time was at the time a Power Train Engineer at GM and Chairman of an oil standards body. He knows what he is talking about. The article originally appeared in a Dec. 2007 GM Techlink publication for GM dealers and technicians titled: “Engine Oil Myths”. GM techlink is not available to the public on the internet.
An Esso oil company bulletin refers to the tests:
http://www.acccc.net/index.php?option=com_wrapper&view=wrapper&Itemid=45.
"Modern passenger car gasoline engines almost exclusively use roller followers,
whether cam-in-block or overhead cam valvetrain designs. Older engines use flat lifters
or tappets which having a sliding, rather than rolling, contact that is much more
susceptible to wear.
The oils in use at the time these engines were produced contained ~50% more
ZDDP than todays oils to provide not only wear protection but some cost effective antioxidancy
as well. Significant concern has arisen among the owners and restorers of these
older vehicles over the correct lubricant selection. Data published by General Motors
(SAE Paper 2004-01-2896 "How Much ZDP is Enough?", Robert M. Olree, Micheal L.
McMillan) indicates that "lower levels of phosphorous, certainly as low as 0.05%, and
perhaps as low as 0.03%" are sufficient to provide scuffing and wear protection for
camshafts in the field."
Starburst (new) oils have a Zddp level of between .06 and .08 percent which is more than what was originally put in oils in the 1940's to address wear issues as you can see in the first link I posted.
Without objective observers and tightly controlled tests I'm not inclined to believe what you think and claim happened in your rebuilds over the automotive engineers who performed these tightly controlled tests, nor do I believe your unsupported claims about GM losing cams left and right in the 70's. For every mechanic like you that makes such claims there's one like my husband who says there's no truth to the claim that modern oils cause excessive wear in older motors and he's rebuilt many using new oils and never seen a failure due to the oil. I've given you the information from GM itself and your welcome to contact them and call them liars if you want but I'm going to take their word for it as well as the rest of the automotive manufacturers over yours every day. People here can read what you posted and what I posted and decide for themselves. Once again, all you've posted is repitition of the myth and no scientific tests to contradict those that were done by SAE.
Those who think they should add zinc to their oil in the form of ZDDP should keep in mind that if ZDDP levels get too high it will cause excessive wear.
Topic: It's a myth that lower levels of zinc in new oils wear out flat tappet camshafts (Read 9928 times)