
Originally Posted by
d_mac
Don't know about Royal Purple, or even say the German-motor oil brand, LiquiMoly.
So far, i prefer Mobil1 Delvac 5W-40, mainly because between the three, it has better kinematic viscosity at different temps, viscosity index, and it got the highest TBN at 12.0. Motul and Torco, respectively, contain about 8.0 mg KOH/g. I may say that is way substantial enough, plus buffer, to protect your engine from the effects of sulphur oxidation formed during the pressure combustion process.
To explain briefly, kindly take note that 12.0 mg KOH/g means also 12.0 ppt KOH, or that is, 12.0 parts per thousand potassium hydroxide per gram of engine oil to neutralise/control the acid formed during combustion process, say with your diesel fuel containing 300 parts per million sulphur. With the Mobil1 oil, therefore, it takes MORE TIME before all its alkaline content (KOH) gets depleted thru series of neutralisation, than when you use the other two oils.
Cheers!