This is a copy of a question I had in the TTR forum. ONLY USE 20W-50 RED CAP. The other viscosities of Mobil 1 use friction modifiers. I just put in the Mobil 1 red cap SAE 15W-50 and the back of the bottle says "API service SL/CF". Does this have the friction modifiers? How can you tell by looking at the bottle. The manual says not to use grade CD or higher, I assume then that the CF is not the appropriate oil. The bottle does not say "Energy conserving". If this is the wrong oil it looks like I may be changing the oil soon. Thanks.