5w-40 synthetic vs 15w-40 synthetic

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Originally Posted By: Solarent
I don't think the grading system is obsolete. I think that alot of people don't really understand what it means because of all the folklore around "a multigrade oil that is a 40 weight that acts like a 0 weight in the winter." This isn't how the J300 really works and perpetuating that just adds to the confusion.

Some of us would just be a little happier if the oil companies were more forthcoming with HTHS, and had it in datasheets as standard practices. Of course, I do realize one can make a very accurate educated guess about the HTHS of 95% of the oils on the market. However, it is a sticking point, and something completely unknown outside of technical people, or at least the BITOG type in the general public.

Originally Posted By: userfriendly
By the SAE allowing the winter grade to slip a grade in use, puts motorists at risk of engine damage in severe cold weather.

Just run more monogrades and that will preclude the grade slipping, right?
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Originally Posted By: userfriendly
It is interesting Zeng, that you post your "guess" is that Delo 15w30 is not VII free, but Amsoil 15W40 "is" VII free.
That sounds like bias reporting to me.

Look at the following figures and evaluate:-
a)VI 111 for Delo 400 SAE30 monograde; and
b)VI 128 for Delo 400 SAE 15W30 (mono or multi?)grade; and
c)VI 141 for Delo 400 XLE Synblend 10W30.(This Synblend does NOT claim shear-stability)
Thus my 'guess' on 15W30 (obviously not Synblend, right?) is not VII-free.

Next >>
d)VI 146 for Amsoil 15W40 ............. where Amsoil claims as "Premium 15W-40 Synthetic Diesel Oil with Superior Shear Stability and Extended Drain Intervals ....... "
Hence ...........
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