Do you need any more?

Someone please explain this to me... I always thought the oil is specified to the engine's design, engineering and application, not the other way around.
Yes, that's correct. The engine is developed and then testing is undertaken to confirm that the oil that may have been assumed to be appropriate, is. Sometimes this can change in service if the oil is deemed inadequate or the OEM, working with the oil company, decides that something is better. This was kind of along the lines of what happened with GM and M1 5w-30, which they spec'd forever, and then their transition to M1 ESP 0w-40.

Sometimes it goes the other way though too. M1 0w-40 (a full-SAPS euro oil) was the original oil spec'd for SRT engines. When SOPUS took over, an SRT-specific 0w-40 was developed, which has no Euro approvals and a pretty vanilla SN/GF-5 additive package; it basically looks like somebody turned your basic EC 5w-30 into a 0w-40. Yet, FCA determined that this was more than sufficient for these engines, none of which have turbos to share the engine oil with.

Ford transitioned a huge list of engines that spec'd 5w-30 to 5w-20 after internal testing confirmed that it was safe to do so. BMW switched between 10w-60 and LL-01 oils for at least one M-car engine (S62). Ford also spec'd 5w-20 and 5w-50 simultaneously for the same engine depending on how the car was configured.

Going back to its most elementary, in the cradle of SBC hotrodding, the "10psi per 1,000RPM" rule came about as the result of engines being built loose for more power and trying to determine what viscosity should be run in them. This was what ended up being sufficient per "back of the napkin", so if you had really opened things up but 20w-50 got you there, well, you were OK.
 
Saps is not "added" to oil, in fact an oil with no SAPS would be ideal hypothetically speaking, but that is more or less impossible.
They are indeed additives, as shown in the Machinery Lubrication article linked in post #12.

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In one of the videos that Bill_W posted, sounds like a little bit of ash is necessary to cushion the valves ...
Kind of interesting! Is that true?
 
So… the European cars. Many are installing GPF (gasoline particulate filters)

 
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They are indeed additives, as shown in the Machinery Lubrication article linked in post #12.

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That is so simplistic as to be almost nonsense; it reads like a last-minute high school assignment. For a start, the element is "phosphorus" not "Phosphorous" and any supposedly technical article that can't get the basics right immediately loses credibility with me. To be really picky, element names are also not capitalised.

Next, phosphorus and sulphur are not additives added to the oil. They are two of the elements that are within some of the additives added to the oil. In this case I assume they are referring to ZDDP, or zinc dialklydithiophosphate. If you know chemistry you will know that "thio" refers to sulphur and of course "phosphate" comes from phosphorus. You also have the zinc there too which, in the case of sulphated ash, is the only element of concern. ZDDP is principally an antiwear additive but also delivers some antioxidancy.

Phosphorus, when burnt, does not block the DPF. Phosphorus does not form an ash, or at least not a tenacious one. And the poisoning effect is mostly in the catalytic converters, which have long-predated GPFs and yet aren't mentioned here.

Sulphur is not an antioxidant additive. It is contained in some compounds used in some antioxidant additives, and naturally-derived sulphur compounds in group 1 base oils can also exhibit oxidation resistance. Sulphur does not block DPFs and DPFs are not blocked by thickened oil or sludge.

Also worth mentioning that ACEA limits on phosphorus include a minimum as well as a maximum in most of the 'C' specifications, meaning you have to have it present.

So with all that said, I wouldn't use that source to substantiate any claims.
 
In one of the videos that Bill_W posted, sounds like a little bit of ash is necessary to cushion the valves ...
Kind of interesting! Is that true?
Well this was one of the benefits that tetraethyl lead (TEL) gave when leaded gasoline was used, meaning valve seats could be softer (usually just machined out of the cylinder head itself) because the lead ash protected them - this is why hardened valve seat inserts are often needed if you plan to convert an engine from leaded to unleaded fuel.

I can see an argument for ash protection of the valves but I'm not clear by what mechanism the oil ash reaches the valve seat, at least not in a controllable, consistent way. My understanding is that valve seats and valve faces are made from materials that naturally resist valve seat recession, along with appropriate cam lobe profiles to avoid 'slamming'.

To think of it another way, if valve seat protection was a requirement of oil performance there would be a valve seat recession test somewhere in an oil specification - I am not aware of one anywhere.
 
That is so simplistic as to be almost nonsense; it reads like a last-minute high school assignment. For a start, the element is "phosphorus" not "Phosphorous" and any supposedly technical article that can't get the basics right immediately loses credibility with me. To be really picky, element names are also not capitalised.

Next, phosphorus and sulphur are not additives added to the oil. They are two of the elements that are within some of the additives added to the oil.
It's most likely written simplistically for a reason. If they are elements within additives put in the oil, then they are basically still introduced additives to the oil. They don't come from the refined crude oil before any additives are introduced.

Also:
 
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It's most likely written simplistically for a reason. If they are elements within additives put in the oil, then they are basically still introduced additives to the oil. They don't come from the refined crude oil before any additives are introduced.

Also:
Sorry, but you can write technical stuff in simple terms without being wrong.

And just because people commonly make the spelling mistake, doesn't make it right. Phosphorous is a different word to phosphorus, with a different meaning (rather like sulphurous is to sulphur or nitrous is to nitrogen). Someone writing an article where chemistry is the underlying subject ought to make sure of getting basic chemistry stuff right, like how to spell elements and the difference between an element and a compound.
 
Sorry, but you can write technical stuff in simple terms without being wrong.

And just because people commonly make the spelling mistake, doesn't make it right. Phosphorous is a different word to phosphorus, with a different meaning (rather like sulphurous is to sulphur or nitrous is to nitrogen). Someone writing an article where chemistry is the underlying subject ought to make sure of getting basic chemistry stuff right, like how to spell elements and the difference between an element and a compound.
It may not be worded exactly accurate, but the basic crux of their point is those elements are introduced through additives. They are not natural elements of the crude oil refinement process. Doubt they wanted to make it a chemestry lesson, but yes, it could have been worded better. The mention of the other spelling was to simply show there is such a word, regardless if used correctly or not.
 
So… the correct term is saps not SAPS. Hmm… Is that right?
Depends on who's writing or reading it. 😄

Most articles use SAPS since it's an acronym, and it stands for Sulfated Ash, Phosphorus, and Sulfur.

PS Sidenote: Noack is Noack, not NOACK.
 
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Well this was one of the benefits that tetraethyl lead (TEL) gave when leaded gasoline was used, meaning valve seats could be softer (usually just machined out of the cylinder head itself) because the lead ash protected them - this is why hardened valve seat inserts are often needed if you plan to convert an engine from leaded to unleaded fuel.

I can see an argument for ash protection of the valves but I'm not clear by what mechanism the oil ash reaches the valve seat, at least not in a controllable, consistent way. My understanding is that valve seats and valve faces are made from materials that naturally resist valve seat recession, along with appropriate cam lobe profiles to avoid 'slamming'.

To think of it another way, if valve seat protection was a requirement of oil performance there would be a valve seat recession test somewhere in an oil specification - I am not aware of one anywhere.

Thanks for your response!

It also didn't make sense to me that engines are designed with leftover ash in mind due to so many variables involved ... but I'm not an expert and that's why I asked the question.

You also have a very good point about oil performance requirements if ash "cushioning" was one of the objectives.
Was there a fuel related performance requirements and test in regards to lead cushioning or was it a known fact or came about with trial and error or luck?

Just a wild guess, assuming IF cushioning was an unintended or unexpected benefit or side effect of ash ... out of curiosity and regarding the mechanism to deliver ash (which is my main question), isn't ash present no matter what? and even more with port DI or DI engines?
I keep reading about IVD and use low ash or dexos oil to limit deposits ... granted it won't be delivered under "controllable, consistent way".

Thanks
 
Thanks for your response!

It also didn't make sense to me that engines are designed with leftover ash in mind due to so many variables involved ... but I'm not an expert and that's why I asked the question.

You also have a very good point about oil performance requirements if ash "cushioning" was one of the objectives.
Was there a fuel related performance requirements and test in regards to lead cushioning or was it a known fact or came about with trial and error or luck?

Just a wild guess, assuming IF cushioning was an unintended or unexpected benefit or side effect of ash ... out of curiosity and regarding the mechanism to deliver ash (which is my main question), isn't ash present no matter what? and even more with port DI or DI engines?
I keep reading about IVD and use low ash or dexos oil to limit deposits ... granted it won't be delivered under "controllable, consistent way".

Thanks
Well… how about piston rings too.
 
It may not be worded exactly accurate, but the basic crux of their point is those elements are introduced through additives. They are not natural elements of the crude oil refinement process. Doubt they wanted to make it a chemestry lesson, but yes, it could have been worded better. The mention of the other spelling was to simply show there is such a word, regardless if used correctly or not.
Fair enough, although I would add that sulphur usually taken out in base oil refinement
Thanks for your response!

It also didn't make sense to me that engines are designed with leftover ash in mind due to so many variables involved ... but I'm not an expert and that's why I asked the question.

You also have a very good point about oil performance requirements if ash "cushioning" was one of the objectives.
Was there a fuel related performance requirements and test in regards to lead cushioning or was it a known fact or came about with trial and error or luck?

Just a wild guess, assuming IF cushioning was an unintended or unexpected benefit or side effect of ash ... out of curiosity and regarding the mechanism to deliver ash (which is my main question), isn't ash present no matter what? and even more with port DI or DI engines?
I keep reading about IVD and use low ash or dexos oil to limit deposits ... granted it won't be delivered under "controllable, consistent way".

Thanks
My understanding is that TEL was used principally as an octane booster - the valve seat protection was noticed as an unexpected bonus, but one that OEMs subsequently took advantage off.

Oil-derived ash comes from the combustion of oil along with the fuel - this is an unintended but unavoidable consequence of how four stroke engines work. Since this happens in the combustion chamber, which is downstream of the inlet valves, these can not get any ash protection. Exhaust valves might pick up some ash but the amount and ability to accumulate will be hugely variable. Fuel-derived ash has a chance of getting to both valves, assuming carburation or port injection.

As a related aside, I have seen what happens to exhaust valves in gas engines (stationary powergen units running on landfill gas) when a particle of hard ash gets trapped in the valve seat - the worst one I saw had around 15% of the valve tulip simply burnt away, like taking a slice out of a pizza. The exhaust gasses effectively acted as a cutting torch and blasted the material away when the seal failed due to the embedded particle and a gas path evolved.

I don't believe that IVD are related to sulphated ash levels as I don't believe that the deposits are ashy, but more carbonaceous/coke (therefore derived from the base oil, VM etc).
 
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