1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Yes, our engines have flat-tappet cams. However it is not clear to me if the overhead-cam design is as susceptible to modern oils' lack of ZDDP as old-style pushrod engines. I recently had the valve cover off my 16-valve engine and it looks like the cam followers are quite large, so loads on the camshaft lobes are well distributed. The cams looked to be in perfect shape with about 250,000 miles on the clock. (Valve cover was off to install oil feeder repair kit for the lifters.)
On my old U.S. domestic iron I've gone to using CI-4/CI-4+ diesel-rated oils that still contain a high ZDDP level, but for the moment am still using new-type "API Certified" oil in my C900. ("API Certified for Gasoline Engines" is Newspeak for "low ZDDP levels.")
One possibility I'm considering is switching to Mobil 1 15W50. This contains 1200 ppm of ZDDP, the recommended amount for flat-tappet cams, and you get the benefits of synthetic oil (better flow, longer drain intervals). But it's not clear to me whether it's necessary.
Has anyone documented cam failures in C900 engines due to low ZDDP levels? I haven't seen any anecdotal evidence let alone hard data, so it's hard to draw any conclusions. My own car is doing OK on modern oil so far but a statistical sample of one doesn't mean much of anything.
One good resource for this type of information is the forum section found at:
http://www.bobistheoilguy.com
Apparently the issue with ZDDP is that it supposedly can poison catalytic converters, particularly on engines that are burning some oil. I'd find it much cheaper and easier to change converters once in a while than to be wiping out camshafts, though!
posted by 209.60.99...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
