Originally Posted By: jeff78
Originally Posted By: ArcticDriver
"“In order for a diesel engine oil to claim an ‘S’ category, it must now meet all of the gasoline category’s criteria, including the limit on phosphorous levels,” Negri continues. “Phosphorous has long demonstrated proven protective qualities versus ashless chemistries in diesel engines, but has also been known to shorten the life of automotive catalyst systems in gasoline engines. This means that diesel engine oil must be below 0.08% phosphorous to claim an ‘S’ category approval [the CJ-4 specification allows up to 0.12% phosphorous].”
I would say that maybe this representative wasn't fully aware that certain limits in API SN only applied to certain viscosity grades, or maybe got misquoted, or something got lost in translation during article publication.....who knows.
The API SN specification is here, you can see the differences in limits between viscosity grades yourself:
http://www.oilspecifications.org/articles/api-sn.php
If they were to force dual rated diesel oils to have a phosphorous limit of 800ppm even for xxW-40 oils, then they would be going beyond simply meeting all of the gasoline category's criteria.
At any rate, it might be best at this point to wait for VOA's of various CK-4 oils to show up before committing to them. Even if phosphorous limits aren't mandated to the lower 800ppm level, some CK-4 formulas may end up at that level voluntarily like the Delvac above.
Excellent post and my suspicion as well.
I appreciate the link and do you have one for CK-4 formulations? Like yourself, I am also waiting for VOAs but even more for UOAs !
Thanks