Originally Posted By: Garak
Originally Posted By: GenaFishbeck
You make some great points Merkava_4, because of those higher zinc and phosphorous levels that you mention, diesel engine oils are not recommended to be used in today’s newer gasoline engines. The top tier diesel engine oils of today are rated as an API CJ-4/API SM motor oil but most newer passenger car vehicles are calling for the newer API SN/ILSAC GF-5 category which has lower levels of the zinc and phosphorous than the API SM diesel engine oils do.
I've asked this before, but it's fallen on deaf ears, but I'm willing to try again. If Shell is so concerned about using Rotella in gasoline engines, why do they obtain a gasoline engine certification on Rotella? They could drop the SM altogether if it's such a concern. Certain Motorcraft and Delvac Elite oils have CJ-4 but lack any SM or SN specification.
If a gasoline engine calls for an SM or better oil in a 5w-40, then Rotella 5w-40 CJ-4/SM fits exactly what the manufacturer called for.
Also, now's as good a time as any to ask the question. Mobil and Chevron each offer an ACEA E6 CJ-4/SN low phosphorous HDEO. Will Shell be following suit soon?
Hey Garak – To clarify, Shell Rotella engine oils meet both the API CJ-4 rating (for “compression” diesel engines), as well as the API SM rating (for “spark” gasoline engines). The API SM rating is backwards compatible with previous-to-API SM-categories, but it is NOT forward compatible with the API SN/ILSAC GF 5 category. Hence, you shouldn’t see a gasoline engine recommendation for an “SM or better” oil, as stated in your post. Frankly, it’s not a matter of API SN being “better” than API SM - they are just built differently, for a different application.
Simply put, a gasoline engine that asks for an SM oil already knows how the SM oil was built and the tests that it had to pass to be certified as an API SM oil. The same goes for SN/ILSAC GF5. If an engine calls for an API SN/ILSAC GF 5 oil, then it is asking for a gasoline oil with the appropriate low-SAPS additive levels and the specific tests that an SN/ILSAC GF 5 oil had to pass, etc.
What all of this means is: Shell Rotella HDEO engine oil might be a consideration for slightly modified performance engines with aftermarket (aggressive) camshafts and sliding followers or even older engines asking for API SM or previous oils (again, engines that might need a higher level of anti-wear agents). For your reference, the Rotella HDEO multi-viscosity oils contain approx. 1,200 ppm of zinc. With that said, we would NOT recommend Shell Rotella HDEO multi-viscosity products for any gasoline engine asking for an API SN/ILSAC GF 5 rated oil. These oils are for engines that only want approx. 800 ppm of zinc. If Rotella HDEO were to be put in an API SN/ILSAC GF 5 engine, there would be an increased possibility of catalytic converter issues (due to the higher amount of anti-wear agents in the HDEO, etc.). Hope this info helps! – The Pennzoil & Shell Rotella Teams