The Castrol claim that it provides 8X the wear protection is explicitly true. In an engine test designed to measure engine wear at low oil temperatures (i.e. start engine, never drive it long enough to warm up, turn off engine) the Castrol oil, according to Castrol, had 1/8 the wear on the camshaft that Mobil 1 did.
SwRI: Sequence IVA Test Method for ILSAC GF-3/GF-4 and API SL/SM
However, both oils passed the test and both oils are API certified. The OEMs, additive companies, oil companies jointly develop these tests and also agree on passing and failing results, so passing this (and any of the tests needed for the API certification) means the oil has met the requirements established by a jury of technical peers.
Furthermore, these tests and the limits are statistically determined as if they are pass/fail. There is no criteria that allow a marketer to say they passed all the API certification tests better than a competitive oil. This is a case of the marketing people cherry-picking and mis-using data.
The engine used is a
Nissan KA24E, a 1996 vintage single overhead cam, rocker arm, port fuel injected engine. It does not have roller followers like all Viper engines have, so the wear being reported by Castrol doesn't matter.
The test
never gets above 130F coolant and 140F oil temperature. This test exaggerates low temperature effects, and at these conditions it may not even the anti-wear additive that matters. Other surface-active molecules (detergents, friction modifiers) that you want in the oil may interfere. At warmed up temperatures the system of additives very likely will work just fine. It may not be that Mobil doesn't have something Castrol does; it could be that Mobil has much more of something Castrol doesn't have as much of.
Also,
by focusing on one feature of one test from the large number of engine and bench tests needed to certify an oil ignores the fact that oils and engines have to operate over a very wide range of conditions. I could design an oil that only works when cold and is terrible when hot (and vice versa.) I think we all want an oil that works (i.e. at a minimum, passes all the criteria) over all the temperature conditions and speeds and loads the engine experiences.
Castrol Edge
(hover over the oil drop and the camshaft)
I'm not a lawyer, but there is case law regarding advertising that advises "it is not what the advertiser says, but what the consumer takes away." In this example, Castrol claims their oil is better, but if consumers (all of you!) take away the idea that Castrol is better than Mobil under all circumstances (and not in just the low temperature, sliding rocker arm wear the KA24E test evaluates), then that is illegal for Castrol to do. They must modify the ad so that consumers understand their claim is based on low temperature, sliding lifter cam wear performance. I would count on about 90-120 days and by then the National Advertising Division of the Better Business Bureau proceedings will take place and the ad will be removed or modified.
*** BBB
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