Originally Posted By: fdcg27
and yet, Shell has said that Rotella should not be used in catalyst equipped vehicles. Why?
Shell is nuts, that's why. They get a modern spark ignition certification yet warn to not use it in vehicles that need SN oil. Go figure.
Actually, though, most of the oil companies warn against North American customers using dual rated oils in catalyst equipped vehicles. I've seen that from Chevron and Petro-Canada, too. XOM seems to have less of a problem with it, and recommends Delvac 1 ESP 5w-40 (and other HDEOs) for high performance gasoline applications.
yvon_la: As I stated elsewhere already today to much the same question, if an HDEO is relatively new, it'll probably have an SN rating. If it was something that existed in CI-4 and CI-4+, the upgrade to CJ-4 was the big one, and SM remained. HDEOs that are more recently available in North America seem to have the SN specification. And no, Delvac 1 LE 5w-30 is not resource conserving. It never will be, either. It cannot be GF-5 rated. It's low in phosphorous, but its HTHS is 3.5 or greater as per its CJ-4 specification, which is listed first on the bottle. Therefore, its HTHS is too high to obtain ILSAC certification. Listing CJ-4 before SM or SN allows them to get away with higher phosphorous, if they so choose. Lacking ILSAC certification altogether is because of the thickness that goes with CJ-4.
We've been through this before. An oil can be SN, but not resource conserving (ILSAC rated). We see this in monogrades, and in multigrade 40s and 50s, and certain multigrade 30s.
But, to be ILSAC rated, it has to have the API rating with it. You can have SM. You can have SN. You can have SM/GF-4 and SN/GF-5. But, you cannot have GF-4 or GF-5 on their own. Again, though, you will never see a resource conserving (or ILSAC rated) CJ-4 oil. The specifications are mutually exclusive.