Any oil experts on here? (SAPS and cam wear)

[Vanya]

Hey everyone,

Was wondering if we had any oil experts here that could shed some light on a matter which is currently causing me a headache (and may well cause all of us a headache down the line when current oils become obsolete):

So recently I bought myself a 2002 Jaguar XKR which had been sitting around for a while. Naturally the first order of business was to get rid of old fluids, starting with the engine oil...

Jaguar recommends a range of viscosities (that's the easy part...) as well as something meeting ACEA A3/98 and API SJ - now these are standards that have been around for quite a while, and have been "superseded", most recently by ACEA C3 and API SN. Now I choose to err on the side of caution and use superseded very loosely here...

Once upon a time, sequential updates of the API register would entail that later = better, so SL replaced SJ which had replaced SH etc etc....but this seemed to change beginning with SM. More on that soon. 

I ended up buying Castrol Magnatec C3 - partly because Castrol's UK oil selector homepage recommended it (but the Swedish page did not...ho hum...), because the Swedish version of Halfords recommended it, and partly because, not being an expert, I figured that its statement of being an oil suitable for modern gasoline engines with 3 way cats (modern? 3 way cats?!) was right up my alley.

So, changed oil, change filter....

But now having consulted the interwebs in its infinite wisdom, it would seem failures have been reported (albeit not outright acknowledged) by motor oil manufacturers, in cars with flat-tappet cams running these kinds of oils.

The marketing blurb for API SN/ACEA C3 is that it provides superior protection for vehicles with exhaust aftertreatment technology (increasingly sophisticated in diesels, but still bog-standard 3 way cats on gasoline vehicles) in that the lower SAPS (Sulphurated Ash Phosphor and Sulphur IIIRC) content is kinder to catalysts. Good news yes?

Except starting with API SM (when lower SAPS limits were imposed) reports started coming in of cars whose cams wore out after very short periods....and I can't seem to find a reliable source confirming this. Indirectly API acknowledges this by not explicitly stating that SN supersedes SM and earlier versions (although SM which is beleaguered by controversy IS a replacement for earlier versions). ACEA has issued a semi-warning saying "It might not be suitable for older vehicles", this because the old SAPS count of (I think) 1500 ppm minimised valve wear.

It would seem that there is an assumption among engine oil makers that everyone is moving on to roller-tappets, which can handle the lower SAPS levels, except to my knowledge, plenty of modern cars still use flat tappets of some sort... 

Now the AJ27 4 liter Jag unit is running flat tappets, so currently I'm looking at another wad of hard-earned cash gone to oil in the space of 2 weeks....not cool.

What's the general consensus on here? Yes the EASIEST thing would have been to buy the EXACT oil specified by Jaguar, but aside from that, can anyone point me to any studies or published works by reliable sources that lend weight to the adage that "mid-saps = high wear on flat tappet engines". I suspect all available oil will be "mid/low" SAPS in future, so it would be good to get a grasp on this beforehand....

Of all the threads I wrote the links to stuff published by API and ACEA were all broken..... 

Looking forward to a grand debate on this matter. It's been a long time coming but I'm finally committed to educating myself a little bit more about the fluids I pour into my cars on a regular basis.... 

 

 

[Bravo73]

Have you asked 'The Oilman'?

http://www.opieoils.co.uk/t-the-oilman.aspx

[Chillidoggy]

I did a lot of research on oil spec quite a while ago for new diesel engines. At the time I found that the oil companies were constantly pushed by the engine manufacturers to develop improved oils. Whether that still holds good, I don't know, but the API list still includes the engine manufacturer's own standards.

I would always go by the API specification, later is usually better, and try to stay as close as possible to the original oil weights. But I wouldn't get too anal about it, either!

[Vanya]

20 hours ago, Bravo73 said:

Have you asked 'The Oilman'?

http://www.opieoils.co.uk/t-the-oilman.aspx

Not yet, but will check.

@ian29gteThey're pushed that's true, but it would seem that legislation has pushed manufacturers for aftertreatment solutions to remain effective longer, to the detriment of engine wear. Of course this could mean that an engine's lifespan goes from 300,000 miles to 250 000 miles or other some such silly high mileage which few ever reach but it's always nice to have some kind of confirmation backed up by hard data. Too many keyboard warriors out there.

I just got off the phone with a Jag specialist who gave me his two cents on the matter - that those engines harmed most by lower ZDDP and SAPS-levels would be old pushrod engines where contact surfaces are small and lubrication sparse...this seems to be in agreement with some of the test results I've read - that a warning was issued when testing on a very old engine design showed higher wear than with full-SAPS/ZDDP oils... 

[Chillidoggy]

250,000 miles? You won't be bothered at that stage, the rest of the car will have fallen apart long before then!

 

[Vulcan Grey]

I'm at 253,000 miles on my 2002 Honda Integra...