Anyone notice Amsoil 5w-40 = M1 0w-40, not M1 5w-40?

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Jun 16, 2003
Franklin, OH

Originally posted by blsnelling:

With this in mind, I would think the Amsoil would be a better oil since the M1 0w-40 likes to thin out and the M1 5w-40 is quite a bit thicker at startup.

The typical data sheets only give that ...the typical data and thats a starting point but in the nd these oils need be ran in the owners engine and how he / she drives to be declared which is better .

My opinion about the M1 0w-40 is no-one here runs it enough miles to see what it's really capable of ..........

Those that don't run it might not need to critic it with such heavy hand IMO because they in affect have no first hand knowledge how it work's in anyone's engine much less their own especially in long term .
I agree with Motorbike. I think the 0w-40 is put down to often for miniscule % changes in viscosity. It's a very shear stable oil for what it is.

Regarding SUV/AFL, they both look nice. If SUV is D1, which their now seems to be some evidence it's not identical, then this is a proven oil. D1 is around 26% ester. Both use differenta chemistries and I'm not sure which is better. If I had to guess,I'd say Delvac 1 is based on it's track record and strong ester content.
The new Amsoil 5w-40 is similar to Delvac 1 in terms of high temp, high shear viscosity.... I think it's an excellent choice for high mileage, worn engines that originally called for 5w-30 or 10w-30. I do expect it to be more shear stable than an SAE 0w-40, which really isn't saying much.

The additive chemistry of the Amsoil 5w-40 is more like the Mobil 1, 0w-40, in that it's optimized for high performance gas engines and passenger car diesels. I would NOT recommend this Amsoil 5w-40 for use in HD diesel engines used in plckup trucks. Both the Amsoil 15w-40 and Series 3000, 5w-30 are better suited to those applications.

HT/HS Viscosity @ 150C/302F:

Amsoil 5w-40 -------4.2 Cp
Delvac,5w-40 -------4.1 Cp

Mobil 1, 0w-40 ------3.6 Cp
Amsoil 5w-30--------3.5 Cp
Redline 5w-30-------3.5 Cp
Castrol 0w-30--------3.6 Cp

The Mobil 1, 0w-40 is functionally more like most of the other, top tier 30wt synthetics ....

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