Chevron 10/30 vs 10/40.

[Chris142]

Kragens got it on sale. I looked at them and the 10/30 is SM rated and the 10/40 is SL.

Since the jury is still out on the SM and flat tappit situiation I bought the SL 10/40 for my Jeep.

Why is one SL and the other SM?

 

[bruce381]

stocking situation takes a long time ? months to work "old" stock out of supply chain. Unless Chevron has not upgraded the 10/30 yet.

bruce

 

[LargeCarMan]

Chris, what year is your Jeep? The SM is the better of the 2, but the SL is better for older engines.

When I purchased the SM, I used it in my Mom's 3.0 Ford van...newer, and my Fathers 440 Chrysler motorhome older got the SL.

 

[MarkC]

I'm using the SM Havoline 10W30 in my Jeep. I'll do a UOA next couple of weeks, we'll see how it goes.

 

[Ron AKA]

quote:

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Originally posted by Chris142:
Kragens got it on sale. I looked at them and the 10/30 is SM rated and the 10/40 is SL.
Since the jury is still out on the SM and flat tappit situiation I bought the SL 10/40 for my Jeep.
Why is one SL and the other SM?

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The GF-4 (SM) standard allows for all 10wXX grades but sets the fuel effiency standard based on 10w30 oil. While 10w40 or even a 10w50 could technically qualify, they likely can't because they can't meet the higher weight specs and achieve the required fuel efficiency.

 

[Chris142]

quote:

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Originally posted by LargeCarMan:
Chris, what year is your Jeep? The SM is the better of the 2, but the SL is better for older engines.

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02, 4.0 non-roller lifters.

 

[Blue99]

Many of the 10W-40 offerings stayed at the SL levels for zinc and phos, since, on a practical basis, this grade is outside the GF-4 fuel economy specifications.

API Licenses for Chevron Motor Oils

Some 10W-40's and straight SAE 30's will have the phrase "meets emission system requirements of GF-4" or similar verbage to indicate that the zinc & phos levels meet the phos restrictions for catalytic converters.