API diesel / gas ratings

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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.
 
Yes, well, at least it did have more of a meaning. Think of CH-4/SL as a dedicated HDEO. Until just recently, an oil with the diesel spec first would have a phosphorus waiver in the so-called ILSAC grades. That's gone. Something like Sx/CF is something you still see in certain grades, but is fairly uncommon these days.

When such a display was more "current," for want of a better term, people who were running diesel engines didn't take them seriously. In that, I mean people wouldn't buy an ordinary passenger car motor oil that said Sx/CF for a diesel, but would buy something that was specifically sold as an HDEO, like Rotella or XD-3; that is, at least if they had any sense.
 
Interesting, here is the reply from Penrite:

Our semi synthetic range covers both petrol and diesel vehicles and are not diesel specific oils. They are added with an additive package to then meet the required specifications. In this case the diesel rating API CH-4 is shown first as it is higher then the petrol rating API SL. If you have any further questions please get in contact.
 
It's also important to note that the CF specification wasn't very robust. Subsequent to that, they got significantly more demanding. Back in the day, it was exceedingly common for ordinary passenger car motor oils to have the Sx of the day followed by something like CD or whatever was current in the day. These were often ordinary 5w-30 grades with reduced HTHS, and those people who put them in their Case tractors, for instance, or on the road tractors, needed their heads examined.
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Now, if you were to give me a Cummins of the vintage where CF was current, there are SL/CF or SN/CF type oils I'd consider using. A lot of A3/B4 oils have an SL/CF or an SN/CF, depending upon grade. That would be suitable for use in such a Cummins. The Penrite motorcycle oil you reference probably would be suitable, too, given that it's probably a 40 grade and Penrite should be able to be trusted to have an additive package representative of what the obsolete CF specification called for. You give me a 5w-30 SG/CD or something like that, I'm not trying it in said Cummins.

Heck, I would suspect that a true A3/B4 lubricant that lists Sx/CF would significantly leapfrom the CF standards and comes close in many ways to what a CI-4 HDEO would offer, particularly in SA and TBN. It's just that in North America, for an "older" diesel, it makes more sense to buy a 20 L pail of 15w-40 than it does to spend large dollars on A3/B4, since A3/B4 here is always marketed as a premium synthetic product.
 
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 .
 
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