What does the sulfated ash % mean?

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Apr 26, 2004
1. Does sulfated ash come from sulfur in the oil? And could that sulfur harm Nikasil cylnider liners? 2. Can sulfated ash deposits be bad for rings? Can it abrade them? 3. With the newer "euro" oils having sulfated ash %-ages closer to 0.5% would you use a oil with a +1%?
Doh! I'd meant to put this in the general topics forums. Mods, help please. Raven, what type of engine? And M1 is selling 5W40 again? I've seen it on their site but not the store shelves. I guess my main question is: Would you use a HDEO in a newer "euro" engine and run an "extended" (7-8k) OCI? And why are the euro oils so low in sulfated ash?
1. Does sulfated ash come from sulfur in the oil? And could that sulfur harm Nikasil cylnider liners?
The ash comes from the metallic oil additives. Sulfur from high-sulfur fuel is what caused problems with NIKASIL. I don't know if sulfated ash from oil harms NIKASIL. You may want to contact the inventor of the material and coating process, Mahle.
2. Can sulfated ash deposits be bad for rings? Can it abrade them?
Deposits can cause sticky or stuck rings, and those cause increased wear.
3. With the newer "euro" oils having sulfated ash %-ages closer to 0.5% would you use a oil with a +1%?
I have no concerns using an oil with up to 1.5% sulfated ash content in an engine that allows that limit. Obviously I would use only a low ash oil in an engine that requires it due to the latest emission system components that may include advanced cats or diesel particle filters.
Thanks, JAG, that's an interesting site. moribundman, could't the sulfated ash come for sulfur in the oil? It's gotta come from the oil if they include it in the oils specs. Like from MoS2 or some other compound? Sulfate = SO4 (had to look it up, my chem sucks). I think I'd just get canned response from Mahle saying not to use HDEO in newer euro engines (not just Nikasil). I've heard sulfated ash causes abrasive deposits. True? False? And just out of curiousity, how is a HDEO hard on cats? Lotsa zinc?
The reason it's called sulfated ash is because the test uses sulfuric acid to insure complete oxidation of the carbon and make the test more accurate. You also get the ash without using sulfuric acid when just burning the oil and yes it is abrasive. The phosphorus part of the ash reacts with the cat. converter, lessening its effectiveness. Don't use a HDEO in a new Euro engine that specifically calls for an oil other than a HDEO oil. Just like a greasy pot, a certain amount of soap will get it totally clean; using more soap won't make it any cleaner and just leave you with extra soap. In an engine, too much detergent can just cause more metallic deposits and ash while not adding any more cleanliness. If you want super clean, use the right synthetic oil and a maintenance dose of Auto-RX where the esters themselves act as detergents.
A long time ago I asked my ex (she was a pharm-chem major) what would be good to clean oil varnish and sludge, burnt HC's, etc. Her answer was another oil. That was odd to me at first but it slowly started to make sense. Lately, I've been wondering if Auto-Rx was an ester, but not using synthetics with it confused me. I didn't know there was natural esters, thanks again for that info (and more). http://en.wikipedia.org/wiki/Ester I found some general ester info here. DIY Auto-RX? j/k So an HDEO would definately be a BAD oil for a rotary (Wankel) engine with oil injection? Seems like most everyone here likes to use HDEO's in an regular car engine. But from what you've said it doesn't seem like that good of an idea?
""So an HDEO would definately be a BAD oil for a rotary (Wankel) engine with oil injection?"" HDEO has higher Ash than a PCMO so if any engine has a problem with ash a HDEO will agravate that condition how much is a matter of perhaps your ability to "feel" it. bruce
If you had a gas engine tuned slightly rich for best power, might the higher ash help control carbon deposits? Im pretty darn sure I can see the ash doing plug reads on bike motors running hdeo. Not sure I like it and have been shying away from diesel oils. But if the answer is yes to the above question, then maybe it's trade off?
In addition, API CJ-4 quality oils containing reduced ash, phosphorus and sulfur are required to ensure the performance and life of exhaust after-treatment devices.
How true is this versus the "ash is abrasive" theory? If ash wasn't a problem before, why is it a problem now with better technology in materials? The europeans have always been at the forefront of emission control and have been pushing diesel, the major bug being particle emission. [ August 15, 2006, 04:13 PM: Message edited by: thwwx ]
According to my chemist (in the oil business) contact, ash is relative to detergent levels in oil. High ash = high detergent. The benefits of high detergents is apparent - extended drains and cleaner engines overall. Detergents help combat acids and moisture. Ash, itself, is said to cushion valve to valve seat making for longer valve life. In older (worn) engines, where more oil is getting into the combustion chamber via rings and valve guides, high ash oils can create more deposits on rings, sparkplugs, and valves. Take a look at diesel specific oils. They are very high in ash content. Simply put, diesel engines need a lot of detergents to keep them clean and to run those long hours. Burning diesel fuel produces a lot of by products. This will change with the new generation diesel engines, fuels, and oils.
I'd guess that compared to a big cat or cummins industrial engine, the newer smaller higher revving european car diesels have quite a bit more effecient and complete combustion? Possibly reducing the soot before it happens, thus requiring less ash producing additive in the oil? Another guess might be the reduction of the AW add's mandated for cat's. If the detergent and the AW add's compete for surface, and they are to remain in balance, you'd have to reduce the deteregent as well?
AFAIK, Japanese diesel engine manufacturers prefer oil with high sulfated ash which is the opposite of European manufacturers. Anybody know why?
They also care less about saving catalysers. I have learnt lately that non of the ________ manufacturers produce Euro IV compliant models, at least not until 2007.
I drive my car with Mobil Delvac 5w40 around 6-7k miles. It`s a European 1.6 HDI engine from Peugeot. Now it`s okey, I`ll inform you if i have any problems. I don`t have EGR, CAT and DPF (fap).
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The lower ash content in newer hdeo´s are simply to lenghten the life time of particel filters and scr cats. Just like newer gasoline engine oil. High ash content are not good for twostrokes wich burn their oil, i can se the same analogy for wankels. Perhaps should a wankel have two oils, one gear oil for the rotating assy and a twostroke oil for the injection part? This is one of the few usages i find that makes me unsafe to recommend hdeo.
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