Does the sulfated ash (SA) level really matter for intake-valve deposits (IVD)?

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I will argue that the sulfated ash (SA) level -- that is the metal content of an oil -- does not matter for intake valve deposits (IVD) in gasoline direct-injection engines. The IVD is mostly composed of coked base oil with ash (metal) additives that doesn't evaporate. It also contains some exhaust particulates (from EGR) etc. However, since the primary building block of the IVD is coked base oil, how much would the SA level really make a difference? The base oil makes roughly 80% of the oil, whereas the ash is only about 1%. Therefore, I will argue that since the IVD is mostly coked base oil, the ash level has a small effect. In order to combat the IVD, the following all help: (1) Higher-quality base oils, such as PAO and POE, or the poor-man's higher-quality base oils such Group III+ and GTL. (2) More antioxidant to reduce the oil coking. (3) More or better detergent and dispersant to keep things clean. (4) More POE or AN to increase the solvency of the oil, which could loosen up some of the coked oil. There doesn't seem to be any research on this other than a faulty Lubrizol field study that compared a superior (Euro IV) low-SAPS oil to an inferior (Euro III) full-SAPS oil, which obviously favored the Euro IV oil, regardless of the SAPS. Any thoughts?
 
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Those are good points. The oil that ends up coming in contact with the valve, has to be able to resist coking on to the valve. The (4) things you listed would all help that. I'm not aware of any testing for IVD's at this point. Your top tier oils will likely be the best choices. Driven DI oils are mostly PAO, some Group III and a little bit of ester. Amsoil is PAO with what appears to be a good slug of V. Mobil 1 is majority PAO/AN (EP/AP). I'm surprised by the Driven oils base oil composition. However, I don't know the %'s so I'm not sure. I do know the SA is .722 for that oil line. Driven still mentions Noack as being important, but their 0w20 is 11% where as M1 AP is 8.9% and Amsoil is 8.5%. Would the ExxonMobil High Temp Oxidation test be indicative of what would happen on an intake valve? [Linked Image]
 
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Originally Posted by Gokhan
I will argue that the sulfated ash (SA) level -- that is the metal content of an oil -- does not matter for intake valve deposits (IVD) in gasoline direct-injection engines. The IVD is mostly composed of coked base oil with ash (metal) additives that doesn't evaporate. It also contains some exhaust particulates (from EGR) etc. However, since the primary building block of the IVD is coked base oil, how much would the SA level really make a difference? The base oil makes roughly 80% of the oil, whereas the ash is only about 1%. Therefore, I will argue that since the IVD is mostly coked base oil, the ash level has a small effect. In order to combat the IVD, the following all help: (1) Higher-quality base oils, such as PAO and POE, or the poor-man's higher-quality base oils such Group III+ and GTL. (2) More antioxidant to reduce the oil coking. (3) More or better detergent and dispersant to keep things clean. (4) More POE or AN to increase the solvency of the oil, which could loosen up some of the coked oil. There doesn't seem to be any research on this other than a faulty Lubrizol field study that compared a superior (Euro IV) low-SAPS oil to an inferior (Euro III) full-SAPS oil, which obviously favored the Euro IV oil, regardless of the SAPS. Any thoughts?
On what basis is the 10-15 yr old Lubrizol study faulty based upon the technology available at the time? What do you continue to believe that intake deposits are a problem across the entire population? Does this question really matter at ALL? No. Frankly it's entirely irrelevant because the ACEA Cx spec was designed for emissions compliance (TWC Gas, DPF Diesel, and later GPF Gas).
 
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I may be wrong but I always thought the oil chemistry for sulfated ash was to keep the particulate filter healthy.
 
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I didn't find the Lubrizol study flawed. Their study was mostly centered on after treatment emissions components which is what happens above the piston and not below it. IVD is, mostly, what happens to oil below the piston. Lowering SAP's started in the 90's to mitigate polluting cat converters. It was proven in a study, which I failed to download and save and cannot seem to find, that the majority of IVD was caused by drivers going too long on oil change intervals and low quality oil not specified by the manufacturer.
 
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Gokhan and Buster or anyone else...what are your thoughts on Redline 5w-30 Euro Series? Link: https://www.redlineoil.com/euro-series-5w30-motor-oil Specs: TYPICAL PROPERTIES ACEA Service Class C3 API Service Class SN/SM/SL/CF SAE Viscosity Grade (Motor Oil) 5W30 Vis @ 100°C, CSt 11.6 Vis @ 40°C, CSt 69 Viscosity Index 164 CCS Viscosity, Poise, @ °C [email protected] Pour Point, °C -45 Pour Point, °F -49 NOACK Evaporation Loss,1hr @ 482°F (250°C), % 6 HTHS Vis, CP @150°C, ASTM D4741 3.7
 
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^that's a nice oil. I actually forgot RL made a Euro oil with lower SA. If only they made their PCMO line like this. Their top tier oils still contain high amounts of Ca which isn't good for LSPI, although some say esters and moly counter that.
 

Gokhan

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Originally Posted by ka9mnx
I didn't find the Lubrizol study flawed. Their study was mostly centered on after treatment emissions components which is what happens above the piston and not below it. IVD is, mostly, what happens to oil below the piston. Lowering SAP's started in the 90's to mitigate polluting cat converters. It was proven in a study, which I failed to download and save and cannot seem to find, that the majority of IVD was caused by drivers going too long on oil change intervals and low quality oil not specified by the manufacturer.
The part about claiming low-SAPS reduces IVD over full-SAPS is flawed because they are comparing an inferior Euro III full-SAPS oil to a superior Euro IV low-SAPS oils. They are supposed to have a controlled experiment to make such a claim, in which they keep everything except SAPS constant. I agree with the oil quality and OCI being important for IVD, as higher base-oil quality, higher base-oil solvency, higher antioxidant content, better/more detergent and dispersant, and shorter OCI all reduce oil coking and hence IVD.
 
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While true about the base oils in the test, again, they were not testing for IVD.E EDIT: They did mention valve deposits briefly.
 
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4WD

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Well got a bunch of M1 AP, VME, and RGT at the AZ clearance … so hope you are right … I could of bought Costco ‘synthetic' for the same price … but I suspect they slip some EHC in that and still meet Dexos minimum standards …
 
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Quote
The part about claiming low-SAPS reduces IVD over full-SAPS is flawed because they are comparing an inferior Euro III full-SAPS oil to a superior Euro IV low-SAPS oils. They are supposed to have a controlled experiment to make such a claim, in which they keep everything except SAPS constant.
Agree. Quite surprised they did that.
 
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Originally Posted by buster
Quote
The part about claiming low-SAPS reduces IVD over full-SAPS is flawed because they are comparing an inferior Euro III full-SAPS oil to a superior Euro IV low-SAPS oils. They are supposed to have a controlled experiment to make such a claim, in which they keep everything except SAPS constant.
Agree. Quite surprised they did that.
Proof? Again, based upon what? What's this "inferior Euro 3"? Euro 4 oils are by definition lower SAPs no?
 
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Originally Posted by 4WD
Well got a bunch of M1 AP, VME, and RGT at the AZ clearance … so hope you are right … I could of bought Costco ‘synthetic' for the same price … but I suspect they slip some EHC in that and still meet Dexos minimum standards …
Don't take Gokhan's comment too seriously. He's straining to draw some sort of conclusion partly off what he deems a flawed study published essentially a generation ago (2006).
 
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My evidence is anectodal but after using 502 oil for twelve years in two different VW's, and now using 504 in an Audi for over two, the difference in tailpipe soot and oil color over time is huge.
 
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Gohkan, I think I found something that I actually agree with you on 100%. IVD comes from inferior oils and/or poor maintenance, not from high SAPS. There's fleets of vehicles with GDI engines using high SAPS oils with 3000+ppm Ca and no IVD issues nor LSPI issues.
 
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Originally Posted by RDY4WAR
Gohkan, I think I found something that I actually agree with you on 100%. IVD comes from inferior oils and/or poor maintenance, not from high SAPS. There's fleets of vehicles with GDI engines using high SAPS oils with 3000+ppm Ca and no IVD issues nor LSPI issues.
That also makes no sense. IIRC Euro 4 oils are by definition lower SAPS. These oils were introduced in around 2006 in order to meet new emissions requirements. A lot has changed in over a decade. Engine turning and PCV systems have evolved over this time as well as the widespread adoption of turbo charging. Consequently a specific amount IVD do not impact all engines the same way. Due to these inherent variations it's wildly speculative to claim that lower-SAPS don't reduce IVD. Gohkan doesn't know whether the base oils for the Euro 3 were "superior" or "inferior" to the Euro 4 oil. He's just assuming they were based on some preconceived notion.
 
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Originally Posted by BMWTurboDzl
Originally Posted by RDY4WAR
Gohkan, I think I found something that I actually agree with you on 100%. IVD comes from inferior oils and/or poor maintenance, not from high SAPS. There's fleets of vehicles with GDI engines using high SAPS oils with 3000+ppm Ca and no IVD issues nor LSPI issues.
That also makes no sense. IIRC Euro 4 oils are by definition lower SAPS. These oils were introduced in around 2006 in order to meet new emissions requirements. A lot has changed in over a decade. Engine turning and PCV systems have evolved over this time as well as the widespread adoption of turbo charging. Consequently a specific amount IVD do not impact all engines the same way. Due to these inherent variations it's wildly speculative to claim that lower-SAPS don't reduce IVD. Gohkan doesn't know whether the base oils for the Euro 3 were "superior" or "inferior" to the Euro 4 oil. He's just assuming they were based on some preconceived notion.
Any test should be keeping variables consistent, that's my issue if that was the case in the study. Oil A should be identical in composition to oil B other than the altered chemistry.
 

Patman

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I still sleep better at night knowing that the oil I'm using in my direct injected Corvette has an SA of only 0.6%, along with a low NOACK of 5.6%. Unfortunately when this supply runs out and I switch to the new version of ESP 5w30, it's higher on both of those values. I can't imagine that's going to be better for preventing intake valve deposits shrug
 
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