No, that test doesn’t prove the new oil is good for old engines

December 1, 2011 | By Richard Prince


While I could comment on your entire response to Mr. Swartz’s question, I will only comment on the last paragraph. Every licensed engine oil, whether it is ILSAC GF-5 or Dexos 1, has to pass engine tests in which wear is measured. One of these tests is in a GMPT 3800 engine that has been retrofitted with an “antique” flat tappet valve train. This special valve train is used precisely because GM and the oil companies want to ensure that the new oils will protect older engines that have flat tappet valve trains. GM paid to develop the test with its antique valve train and the oil companies pay to run their oils in this Sequence IIIG test. So your last paragraph could not be farther from the truth.


Mr. Olree is referring to my April response to Bob Swartz’s question about whether oil meeting the new standard called GF-5 or Dexos is good for vintage vehicle engines, including those that are over 100 years old.

I stated, in part, “One such substitute that pertains to your question about flat tappets and ZDDP is the inclusion of molybdenum, a rare and very expensive trace element that will substitute for zinc as an anti-wear component. Will molybdenum provide good protection for flat tappets in old engines? Probably, but without valid testing or enough long-term statistical data nobody can say for sure. And not surprisingly, nobody has actually tested the effectiveness of oil meeting the new specification in antique engines and neither GM nor the oil companies intend to at this point.” Mr. Olree apparently takes issue with this and states that it “could not be farther from the truth.”

With all due respect, I stand by my answer. Nobody, including GM, has tested the effectiveness of oils meeting the new standard in antique engines.

The Sequence IIIG test you mention entails measuring the wear of certain engine parts in a 1996/1997 231 cid Series II fuel-injected General Motors V-6 fitted with flat tappets.

Using unleaded gasoline, the engine runs for 10 minutes initially as an oil leveling procedure and then speed and load gradually increase over the next 15 minutes. The engine then operates at 125 bhp, 3600 rpm, and 150° C oil temperature for 100 hours, interrupted at 20-hour intervals for oil level checks.

I stated that neither GM nor the oil companies tested the new oil in antique engines and I am quite correct because a late-model 3.8-liter fuel-injected V-6 equipped with flat tappets is a world away from antique engines. And furthermore, the test specifications—engine horsepower, rpm, and operating temperature—are also markedly different from the real world ways in which many antique vehicle engines operate.

Many antique engines have much broader operating temperature ranges than the test engine, or for that matter, than nearly all late model production engines. Many antique engines, particularly those from the muscle car era of the 1950s and ’60s, have higher rate valve springs and more aggressive cam profiles than the test engine.

Between oil changes many antique engines run with “dirtier” oil than the test engine or nearly all late model engines. Many antique engines have antique cams and lifters that may not, by virtue of how they were made, what they were made from, and how they’ve worn and degraded over time, resist wear as well as a modern camshaft and lifters. Many antique engines have less thorough and less effective oiling systems than many late model engines, and the effectiveness of the oiling systems in many older engines has diminished over time.

For all of the foregoing reasons and more, it is my opinion that the Sequence IIIG test does not accurately predict how oils meeting the GF-5 and Dexos I standards will perform in antique engines.