About a year ago, I wrote about recent changes in engine oil packages that pose threats to older, flat tappet camshaft operated car engines. In essence, manufacturers removed zinc dialkyldithiophosphate (ZDDP) from oils to minute trace amounts in order to satisfy upcoming regulations for new diesel and heavy truck emissions. Word is new trucks will be running catalytic converters and Zinc is known for fouling them up. Car manufacturers years ago switched to roller camshafts for mass production and those style cams don't require added zinc protection the way older, surface hardened gray iron camshafts do.
The results of using the recent formulated low zinc oils have been catastrophic. Camshaft failures inside of 300 miles is common, especially on new engine builds. Older engines with a bit of zinc embedded on the lobes will stay protected for maybe one oil change cycle but then they're in danger. When I last wrote about this topic, the suggested solution was to add engine oil supplement (EOS) or use a synthetic grade motor oil. Since then, another alternative has arrived.
Union 76 HIgh Performance Motor Oil, Kendall GT-1 High Performance Motor Oil 20W50 and Phillips TropArtic Racing Motor Oil 20W50 are being reformulated with more ZDDP starting in March 1, 2009. These oils will contain 1200 ppm of zinc which is the required amount to provide cams with antiscuffing, antiwear and oxidation inhibition.
Some Questions and Answers about engine wear and ZDDP
Q:Why do the older camshafts wear out quickly without ZDDP?
A: Older flat tappet cams such as the 428 CJ, Ram Air IV, LS-6 and LS-5 and other high performance engines were surface hardened only. A car with high spring pressures and not enough zinc in the oil can wear through the protective surface very easily. Pitting, uneven lobes, severe wear patterns appear very quickly. As the camshaft profile changes, power loss occurs.
Q: Other than losing a cam and lifters, are there other dangers?
A: Yes, we've seen a few of these engines stripped down last summer and witnessed camshaft bearing wear and lopsided bearing journals. A significant amount of displaced metal appears in every case. If the metal isn't found in the oil pan, it is somewhere inside the engine block, in an oil gallery or pump main. In such instances the reccommended procedure is to tear down and flush the block to remove loose metal. That's the only way to assure no further contamination. At the very least, the cam bearings must be changed.
Q:My engine is a fresh rebuild. I lubed the camshaft with the factory supplied lube. Do I need this EOS additive?
A: After you've done your initial engine break in, You drop the oil pan plug and change to fresh oil. It doesn't matter which brand you pick, likely it will have less than 1200 ppm of zinc. That protective goo on the cam is for the most part, gone now. It did its job during break in. You still need to use EOS or one of the new formulated oils at the top of the article for protection.
Q: My car is street driven and I use 10W30 oil. Wouldn't switching to a heavier grade of oil reduce horsepower?
A: In more recent engines where tolerances are tighter, say a 4.6 Ford or the last of the 5.0 Mustangs, you might lose some power. The 5.0 liter Cobra engines from 1985 and up used roller cams so it's not an issue the way flat tappet cams are. If you want to keep using 10W30, try an additive instead.
Q: Where can I get EOS additive?
A: General Motors Canada has the additive for sale. It's been reported the product is no longer in service at US dealerships with an invalid part number. Likely lots of dealers have old stock available. Competition Cams sells bottles of their own brand. Either will work fine. ZDDP or zinc is the ingredient you want.
See also "Flat Tappet Camshafts Need Zinc!" from April 18, 2008
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