The Truth: ~ About Oil... and the BULLSH!T about it.

[Rory Phoulorie]

Is an oil with a "SM" rating automatically superior to an oil with a "SL" rating?

I usually use the Shell Helix 20W-50 in the yellow bottle which has an API rating of "SL". I noticed that the new NP Ultra (20W-50) has a "SM" rating. Does this mean that the NP Ultra is superior to the Shell Helix?

Does anyone have experience with the NP Ultra oil? I have heard people talk about sludge forming with NP oils.

[Red Dawg]

Oil Ratings are set by the American Petroleum Institute (API)
The API test each manufacturers oils to verify that they meet the requirements as set by them.
An engine oil should only carry the rating if it has been certified by the API. Apart from the rating on the bottle, there should be the API seal, usually on the back label.

At one time NP used to sell oil with the rating but without the API seal which to me meant that it was designed to meet the API rating but it was not verified or certified by the API.

As the SL and SM ratings are concerned, each new oil rating covers all previous ratings before it. So, SM replaces SL but before you buy, look for the rating seal.
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