We “hear” a lot of times that an oil (actually the VII) has mechanically sheared but it is nearly always backed up with a UOA that cannot distinguish between mechanical shear and fuel dilution.
Royal Purple vs Competitors
- Thread starter buster
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If you have a VOA of that exact batch of oil to compare KV100 and KV40, and you have accurate fuel and water dilution numbers from GC (ie: NOT Blackstone), then you can calculate a ballpark area of where the viscosity should be from dilution alone. Even then though, there's oxidative thickening to take into account. If an oil starts at 10.5 cSt, ends up at 9.0 cSt after 5,000 miles and 2.5% fuel dilution, then it would appear about half of that viscosity loss was from fuel and the other half was from permanent shear. However, the oil would've thickened from oxidation to that 9.0 cSt point. In reality, the oil was likely down around 8.0-8.5 cSt before thickening to 9.0 cSt. Even if an oil shows the same KV100 after 10,000 miles, the reality is that the oil likely fell -1.0 to -1.5 cSt with use and oxidative thickening brought it back up to the starting KV100. A high amount of soot in the oil will also increase the KV100. The margin of error of the viscometer is also a factor. There's a good bit that factors into understanding a given UOA result.
Completely… I had some discussions with a former RP exec who left RP when they were bought. From what it sounded like, Calumet literally slammed the brakes on new development, other than where there were corners able to be cut. Getting distribution thru WM allowed them to profit off the name while delivering a product that had no distinction from anything else on the shelf, other than their former glory as a racing brand.
Yes, at the time, Synerlec was impressive, and still has decent properties for an older additive. To the comment above about XPR having 4 times the Synerlec: nearly all of the “high end” additives have recommended doses of roughly 0.5-3%. So XPR may have the max 3%, the lower tier 0.75%. What you don’t know, however, is if a heavier treat rate brings any additional benefits. And RP hasn’t published any data on that.
Another good reason why UOA are not the indicative tool people keep thinking they are, with multiple interactions that cannot be discriminated by this simple test. The real test for shear stability doesn't allow for oxidative thickening for example, and keeps the singular variable of mechanical shear isolated.
Plus fuel in the oil can in and of itself cause degradation of the VII both temporary and permanent, in addition to simple dilution.
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Since we are on the oft spoken of topic of fuel dilution. Where does it really come from? Unburned fuel past the rings, I get that. But, wouldn't that gasoline flash off in a 200+ degree oil?
I'd assume this is worse on GDI engines (I really don't see the benefits of GDI) a port injected or even carb'd engine would have less fuel dilution? Obviously carbs can leak fuel into the intake and wash cylinders, but that is an antiquated point.
I'd assume this is worse on GDI engines (I really don't see the benefits of GDI) a port injected or even carb'd engine would have less fuel dilution? Obviously carbs can leak fuel into the intake and wash cylinders, but that is an antiquated point.
Here's some data collected on pump E10 gasoline. Note the distillation curve...
With port injection and carburetors, the fuel is passing by a hot intake valve, onto a hot piston top, in a hot chamber, etc... there's plenty of heat there to vaporize the fuel before the ignition event resulting in a complete burn of the fuel. Fuel must be a vapor in order for combustion to take place. It will not ignite as a liquid. The issue with GDI is the same as diesel injection causing the same fuel dilution problems. The fuel is injected into the chamber right before the spark happens, the light ends of the fuel will vaporize almost instantly from compression heat, but the tail end likely doesn't prior to ignition happening. There's just not enough time. So you get a partial combustion of the fuel while the (still liquid) tail ends of the fuel ends up catching in the oil on the cylinder walls, washes past the rings, and ends up in the sump.
If you were formulating a gasoline specifically for GDI engines, you'd have the 0-50% distillation points about the same, but the tail end would be significantly lower, being fully vaporized by 230-250°F instead of 380°F. It would have a lot more light alkane content and less heavy aromatics. The problem then is that it would produce more emissions. Just like with engine oils, you're fighting that battle between engine reliability and emissions.
Diesel engines suffer the same problem and much worse. Diesel doesn't start to evaporate until ~400°F can be 600-650°F before fully evaporated. Even less of the fuel is combusted with each cycle, but it also has a leaner stoich than gasoline so the effect is diminished by that a little bit. Plus they have a much bigger sump in which to spread out the dilution.
A diesel with a 15 quart sump and 3% fuel dilution has over 14 ounces of fuel dilution, almost half a quart. A gas engine with a 4 quart sump and 3% dilution only has 4 ounces of fuel dilution. As the distillation curve of the fuel increases, so does the fuel dilution.
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With mine it most likely wouldn’t be fuel dilution, it was bellow fuel dilution levels and it’s a port injected engine, however my engine does have a pretty robust timing chain setup…double overhead cam, V6, with two chains also connecting the cams on each head (three chains total).
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Yeah, I agree without a VOA of the exact batch of oil I used, tough to say how much it sheared.
Looking at it, what do you think? I thought the oil performed great, then again the engine is easy on oil historically (so most any oil probably would have done well).
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Most engine oil doesn't even reach 200F. 60 C is the required temperature for fuel to start separating out from the oil and vaporizing. This takes 30 minutes or so of constant driving, if not more (in colder climates). Unless you are driving on track, or are pushing your car really hard, the average GDI driver doesn't reach or stay in the required temperature zone to do this.
wemay
Site Donor 2023
Image originally posted by Buster.
B
Wow, i can't believe that VWB (Conventional) showed less viscosity loss than M1 Annual Prot.
Wow, i can't believe that VWB (Conventional) showed less viscosity loss than M1 Annual Prot.
The plant that I work in, Ineos LAO PAO at Chocolate Bayou, is the main supplier of PAO base oil for Royal Purple.
Does RP variant Premium Synthetic High Performance 5w40 have PAO?
Is this the one that's available there in Indonesia?
Yes, this type of oil is available in Indonesia
Would lack of fuel combined with a loss of viscosity indicate mechanical shear?
OVERKILL
$100 Site Donor 2021
Assuming GC fuel, yes.
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typos in the description /
are you sure it's the real thing?
are you sure it's the real thing?
Three typos within four consecutive words, and the word they got right is "the". That's not a good sign.
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