15w40?

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03-31-2015, 07:43 AM

#61

bigbadon

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Year: 2004

Model: Grand Cherokee

Engine: 2000 4.0

Quote:

Originally Posted by Larry's XJ

Unless they changed how they measure viscosity, 40w today would be the same as 40w from the "old days" , and the same as even "older" days

15-40 is NOT the same viscosity as straight 40. 15-40 is a 15 weight base oil with polymers added so it behaves like 15 weight oil when cold and protects like 40 when hot.

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03-31-2015, 08:00 AM

#62

jeepkid03

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Location: Coventry, CT

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Year: 2000

Model: Cherokee

Engine: 4.0 high output, Alabama Cylinder head, 60mm bored TB

Some of the newer diesels recommend a HDEO 10w30. One is the Ford 6.7 and I know a bunch of guys running diesel 10w30s like Rotella T5 in their Duramaxes with great wear numbers.