Originally Posted by KiwiBiker
Many oils have dual API ratings, e.g. a Penrite motorcycle oil that I use is SN / CF. I have recently started using a Penrite semi-synthetic oil, which is rated CH-4 / SL.
Does the order of the gas and diesel ratings mean anything? ACEA Ax / Bx oils always start with the A rating, so I'm guessing there's a reason why sometimes API ratings are reversed.
For ACEA ,between 1996 and 2004 the gasoline (Ax) and Diesel (Bx) categories were separated.
http://www.lubtech.jp/acea_a_b_c_e_2004.pdf
http://www.lube-media.com/wp-conten...eneedsofILSACGF3intheUSAandelsewhere.pdf
http://www.roverworld.com/Downloads/oilsequences2002.pdf
Even then the placement of the resp.category (first or second) would not matter much(as long as both were present on the bottle).
Now,with the combined gas/diesel they always look like Ax/Bx .
There is some common sense in the way they arrange the HD and PC categories on mixed-fleet oils. A dedicated HD oil label with gasoline ratings would look like the Penrite (for example API CH-4/SL ; ACEA E7/E5/A3/B4 . Sometimes the gasoline ratings may be omitted on the label of the canister,as these were not the main application. Sometimes there may be an OEM approval omitted on the label but can be found on the technical data sheet etc.Some of these will have an OEM approval for transmission or retarder use) .
And then it's the OEM approvals that matter most. Some of these mixed-fleet HDEO carried PC OEM approvals too (like MB 229.1 along with the HD MB 228.3 or a Volkswagen passenger-car diesel rating).
Yes, it would be interesting to see how a contemporary ACEA A3/B3 ; A3/B4 API SL/CF PC oil performs in an old HD diesel that required API CF or CE .