Originally Posted By: fonecord2
What will happen if you use a non-rated oil like the rp 10w-30 in a diesel?
Additionally, the thickness might be an issue. Even the older RP 10w-30 SL stuff was still an ILSAC type 10w-30, just with the GF-3 specification. That's on the thinner side of a 30, whereas a 30 grade HDEO is on the thicker side of things, with an HTHS of 3.5 or higher. RP does have HDEOs, and their 10w-40, 5w-40, and 0w-40 grades at least at one point displayed some older API diesel specifications.