article about oil dilution from alcohol based fuels

SubieRubyRoo

SubieRubyRoo

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“LSJr said:
“It’s important to use the proper viscosity designed to work with alcohol-based fuels because high fuel dilution will lower the oil’s viscosity. High fuel dilution can change the oil’s viscosity from 20w-50 to 10w-30, thus reducing the wear protection. So, in high-performance engines, you want all the protection you can get while turning high-RPM and not compromising the oil’s wear protection.
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One would think if fixing the W rating of used oil was this simple, that oil companies would work with auto manufacturers to ensure a minimum amount of fuel dilution. Waitaminute…😳

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Alcohol has a very low freezing temp (-173°F for ethanol, -143°F for methanol) and thus has a significant impact on CCS/MRV. It's actually the 30 grade side that's misleading here as the boiling points of ethanol (174°F) and methanol (149°F) ensure both are evaporated when measuring KV100. The KV40 would definitely be impacted. This would be relevant to a drag engine where the oil rarely sees >150°F.

Let's say you have a 20W-50 with a KV40 of 155 cSt. A drag engine on E85 can have upwards of 10% dilution. That's sufficient to drop the KV40 from 155 cSt down to 86 cSt, a typical KV40 for a 10W-30 oil.

So I don't see anything wrong with his statement except that a KV100 couldn't be accurately measured with alcohol dilution.
 
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But alcohol dilution come through the piston ring pack and the alcohol s in contact with the hot cylinder walls and ringlands. Yet some alcohol still gets through so in practice the kv and HTHS will be impacted even if we can't measure it accurately.

I don't see any real issue with his statements either.
 
My point was, how could it affect the winter rating? Ppl on the board have been told that if you mix say a 0w30 and a 10w30, the oil will still perform roughly equal to the higher number (10 in this case) because there are still parts of the oil that will solidify? Plus, throw in the fact that the W rating can slip a grade worse (so 5w30 acts like a 10w30)… and so I’m just genuinely asking if the dilution actually improves the winter rating.
 
SubieRubyRoo said:
My point was, how could it affect the winter rating? Ppl on the board have been told that if you mix say a 0w30 and a 10w30, the oil will still perform roughly equal to the higher number (10 in this case) because there are still parts of the oil that will solidify? Plus, throw in the fact that the W rating can slip a grade worse (so 5w30 acts like a 10w30)… and so I’m just genuinely asking if the dilution actually improves the winter rating.
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I don't believe that people mean mixing 0W-30 and 10W-30 doesn't affect the winter performance, but you can't be sure you're getting a 5W-30 out of it, and we can't test it either. So assume you still get 10W-30 winter performance and be safe.

I mixed some 2-stroke oil with a vegetable oil once and just because I could I threw it in the freezer at 0F. The vegetable oil by itself would turn into a solid above freezing already, but the mix was still quite fluid at 0F, just cloudy.
 
SubieRubyRoo said:
My point was, how could it affect the winter rating? Ppl on the board have been told that if you mix say a 0w30 and a 10w30, the oil will still perform roughly equal to the higher number (10 in this case) because there are still parts of the oil that will solidify? Plus, throw in the fact that the W rating can slip a grade worse (so 5w30 acts like a 10w30)… and so I’m just genuinely asking if the dilution actually improves the winter rating.
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It seems like the winter rating would change because the ratio of viscosity modifier to base oil would change.
 
CarlB said:
It seems like the winter rating would change because the ratio of viscosity modifier to base oil would change.
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Doesn’t have anything to do with viscosity modifiers, which is a guess anyways if the lower winter rating has more or not. It has to do with the temperature that the waxes in the base oil fall out of suspension because they’ve solidified. That’s why the highest winter rating you’ve mixed will determine your lowest workable temps.
 
SubieRubyRoo said:
Doesn’t have anything to do with viscosity modifiers, which is a guess anyways if the lower winter rating has more or not. It has to do with the temperature that the waxes in the base oil fall out of suspension because they’ve solidified. That’s why the highest winter rating you’ve mixed will determine your lowest workable temps.
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If mixing them doesn't change the winter grade. Then what's the centipoise impact of fuel and water?
 
I was under the impression that the W in multi-grade was based on a cold cranking simulator centipoise measurement while cold, but that the viscosity grade was based on flow characteristics (pouring) while hot.
 
SubieRubyRoo said:
Doesn’t have anything to do with viscosity modifiers, which is a guess anyways if the lower winter rating has more or not. It has to do with the temperature that the waxes in the base oil fall out of suspension because they’ve solidified. That’s why the highest winter rating you’ve mixed will determine your lowest workable temps.
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Mix some veg oil, which solidifies above freezing temps, with any engine oil (including 2-stroke) and put it in the freezer. it gets cloudy and waxy but doesnt become solid even at 0F. I tried it. Did it with diesel fuel aswell, same result. Th waxes don't fall out, they stay suspended.

But you don't KNOW how much lower the winter rating becomes, so it's definitely best to go with the worst winter rating you have in the sump.
 
Only way to know the actual W rating of mixing two different multi-viscosity oils would be to test the mixture for CCS and MRV viscosity. Whereas for KV40 and KV100 you can use a viscosity mixing tool that's pretty valid for temps of 40C and above. There's no accurate "W" viscosity mixing tool that I know of.
 
CarlB said:
I was under the impression that the W in multi-grade was based on a cold cranking simulator centipoise measurement while cold, but that the viscosity grade was based on flow characteristics (pouring) while hot.
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The W grade rating and KV100 grade rating (the 2nd number in a multi-viscoity oil grade) are measured differently, and speced differently per SAE J300 requirements. KV100 is measuring the hot Kinematic Viscosity (how fast it flows under the force of gravity, in units of cSt) at 100C … that's what "KV100" means. The W rating is based on dynamic viscosity (units of cP) under mechanical shearing in the CCS and MRV testing machines.
 
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