Using M1 FS 5w40 in a dry clutch 150cc mopped

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I always used M1 FS 5w40 in everything with an engine with pretty good results regarding OCI, oil consumption, etc. Castrol Edge and Shell Helix are good options when M1 plays hide and seek.
I own a 150cc mopped with a 25k+ miles on it and mechanics are impressed with its particular engine condition except that it suffers from oil dilution in the last couple of years. The manufacturer calls for 10w30 or 5w40 so I opted for the later since it is more appropriate for ambient temperatures all year long and I use it for my car as well.
A lot of people advice me against the 5w grade and say that wide spread grades are less shear stable and that 20w50 is a better option. (Summer can be north of 100+ F) I'm quite reluctant to believe that 20w50 is necessary in a small air cooled engine application and I used it once and the engine seems to feed on it . And FS 5w40 is a robust PAO/GTL based that seems to be almost universal in all conditions and it barely consume only 150 ml from a total of 1000 ml in 700 miles compared to 400 ml running Dino 20w50. Should I change to higher viscosity 20w50 synthetic to get better Noack? And if you agree on 20w50, would you please recommend me a few good oils that are not JASO MA or inferior MB rated? I need something Full SAPS, PAO based because GTL may fall short in this viscosity range AFAIK. This engine really runs hot (Noack is a crucial property of the oil)
 
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It's technically true that a 5w can be less stable than a 20w but sometimes the lower W rated oil gets a much much better base stock to be able to pull off the characteristics and can end up with better stability in the end. But another good oil with great performance would be 15w-40. Low noack. I don't know what heavy duty engine oils are available but you can get a list and find the pdf's of them and see what best suits you.
 
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A lot of people advice me against the 5w grade and say that wide spread grades are less shear stable and that 20w50 is a better option.
People advise but 5w is not a grade test nor is it a shear stable test...
5W is a cold crank test to assess the low temp performance... The
better the performance the lower the W number so the test notes 5W is
better during cold starts than 10W or 15W or 20W... it has been
reported that Roughly 60% of total engine wear occurs during cold
start up conditions before oil can circulate through the engine...


ColdCrankSim.jpg
 
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BigTimeTA

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Would Mobil 1 Racing™ 4T 10W-40 fit? Can it be found there?

People advise but 5w is not a grade... 40 is the grade of the oil...
5W is a cold crank test to assess the low temp performance... The
better the performance the lower the W number so the test notes
5W is better than 10W or 15W or 20W... because Roughly 60% of total
engine wear occurs during cold start up conditions before oil can
circulate through the engine...

Technically speaking 5W is not a shear stable test...


View attachment 98853
Although I am not very deep about technical lubricants stuff, you did really confirmed my thought that low temperature performance is a expressed solely by a good base to begin with and in this case, I would like to know if the Dino 20w50 which is Group II/III blend did shear more regardless of its viscosity due to having bad VI?
 
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Although I am not very deep about technical lubricants stuff, you did really confirmed my thought that low temperature performance is a expressed solely by a good base to begin with and in this case, I would like to know if the Dino 20w50 which is Group II/III blend did shear more regardless of its viscosity due to having bad VI?

As Blackstone's report states there are no reason to fear the shear...
its harmless because as our oil shears flow increases... increase flow
is harmless because our oil serves as a "wall" only when it is constantly
FLOWING between parts keeping them from touching...

full-45634-35394-viscositytest1.jpg
 

ZeeOSix

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As Blackstone's report states there are no reason to fear the shear...
its harmless because as our oil shears flow increases... increase flow
is harmless because our oil serves as a "wall" only when it is constantly
FLOWING between parts keeping them from touching...
Is that what they said, or your interpretation of what they said? In either case, it's all a bunch of BS, and I don't mean BlackStone, lol. Blackstone knows nothing about tribology, as has been show over and over based on your "quotes" by them.
 
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It's technically true that a 5w can be less stable than a 20w but sometimes the lower W rated oil gets a much much better base stock to be able to pull off the characteristics and can end up with better stability in the end.
Yes, the 0w40 version of a certain automotive oil *ahem* is commonly considered (by BITOG members) to be superior to the 5w40 version of the same oil. Key word here is "sometimes."
 
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Yes, the 0w40 version of a certain automotive oil *ahem* is commonly considered (by BITOG members) to be superior to the 5w40 version of the same oil. Key word here is "sometimes."
Referring to the 0w-40 versions of castrol and mobil? I've been told they're better than their 5w-40 versions so that's what i was getting at with my statement.
 

BigTimeTA

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Referring to the 0w-40 versions of castrol and mobil? I've been told they're better than their 5w-40 versions so that's what i was getting at with my statement.
Yeah, I did notice the pour point is a result of high quality base stocks and additives. Nothing beats M1 FS 0w40 to the -60 pour point. A lot of oils in this viscosity range are doing something around -42 to -52. Low temperature performance = Superior base stock/Higher PAO percentage in the blend. But to be fair to the GTL based stocks, even though it falls short in low temperature, although slightly, it still offer slightly better Noack and very comparable oxidation stability. I would choose 0w40 over 5w40 every time if it is on the shelves. I remember some members here are saying that 5w40 is a GTL based, I wouldn't mind using it at all. So the key word is "sometimes better" might be true in the area of low temperature performance".
 
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And if you agree on 20w50, would you please recommend me a few good oils that are not JASO MA or inferior MB rated?

Strictly as an FYI; I'm not trying to derail or confuse, but just as a side note. This stuck out at me.

MB is not a lesser or inferior rating than MA, MA1, or MA2. JASO MB is engine oil meant for engines that don't share sumps with the clutch. JASO MB oils should generally be superior than MA, MA1, or MA2 in those systems since they meet all the same engine performance specs as the other ratings except the clutch friction coefficients/indices are lower.
 
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