SAE J300, HTHS and CI-4

[widman]

If the 1999 SAE J300 standard raised the HTHS requirement to 3.7 cP for a 15w40 oil, what was gained by raising the CI-4 to 3.5 cP?

 

[TooSlick]

I believe the 3.5 Cp minimum spec is for xw-30 lubricants meeting the CI-4+, specification....

 

[Curious Kid]

It's interesting that you noted the CI-4 rating requiring a HTHS of at least 3.5. For those wondering what the HTHS rating for Rotella T Synthetic's 5w-40 oil, it must be 3.5 or higher due to it being CI-4 certified. Didn't note it being spec'ed for SAE J-300 though, so that might put it at 3.5 or 3.6.

Thanks.