Delvac has been formulated within the phosphorous limits of API SM and later, HDEO can be dual rated so long as it complies with both the S-rating and C/F-rating limits. HDEO can no longer be dual rated if it exceeds the S-rating limits as was historically allowed.
If it's just CK-4 or just SP it would be allowed to exceed the 800ppm limit, but dual rated oils are limited to the same limits as API Resource conserving grades.
40 weight isn't an API Resource Conserving grade, so it is (was?) allowed to be higher. Weird to see a recent dual rated HDEO, though, I thought that went out with the switch to CK-4.
40 grade is not resource conserving, so if it's just S rated it can exceed 800ppm, CJ-4/CK-4 allow up to 1200ppm of phosphorous, but at some point shortly after the introduction of CK-4 and FA-4 the API and oil manufacturers reached an agreement that they would no longer allow HDEO to be dual rated if the phosphorous exceeded the S-rating limits, I'm too lazy to pull it up right now, but I seem to recall the exact wording in the API 1509 document says that if an HDEO is CK-4 and also claims SN or SP that the phosphorous must be held to the limits of API SN/SP resource conserving grades. I do believe some oils were licensed prior to the API making this decision so some CK-4\SN oils actually do exceed the 800ppm limit and can continue claiming so until the license expires.
All C-rated oils have to have an HTHS above 3.5.Was sipping a nice Colombian roast when I noticed the first link was related
Here is another below. BTW: even the 10W30 is a 3.6 HTHS …
https://www.mobil.com/en/lubricants...ants/products/mobil-delvac-1300-super-15w-40/
I know … but subject had gone to “starburst“ lubes …
