I know we're obscessing here, but hey, that's what we do, right?
I was reading some technical papers on lubrication, and studies done for Porche, NASCAR, and VW, and found some interesting information. While it seems generally accepted that slightly higher Zinc/Phos levels are good for lots of heavy duty, hard use engines, the jury is still out of the detergent content. It seems high detergent oils, (HDEO) tend to wash cylinder walls down, preventing proper lubrication, and also, can wash away the boundary layer of anti wear additives, such as zinc/phos, moly, boron, etc. Racing oils which have quite high anti wear add packs, but little detergent, seem to have proven this fact out rather well. It seems in diesel engines the oil (with these higher detergent add packs) is pretty busy dealing with blowby and soot, and doesn't get to the point of washing away needed lubrication or boundary wear additives. It's quite and interesting supposition, that we, as Americans, have always adhered to the "more is better" theory, and here's yet another case it may not be true. Now, a lot of these oils are what are known as "mixed fleet" oils, and have spark ratings, but what exactly does that mean? The ILSAC rating for Xw30 oils limits the zinc (actually phos, but they're linked) content to something like
It would seem, at least from anecdotal data, that HDEO oils are doing just fine in air cooled engines, but could it just be that the manufacturers do know a thing or two about lubrication? I think we need to do some more reading. I'm not ready to go back to straight 30wt, or PCMO yet, but I'm interested in the theory.
I was reading some technical papers on lubrication, and studies done for Porche, NASCAR, and VW, and found some interesting information. While it seems generally accepted that slightly higher Zinc/Phos levels are good for lots of heavy duty, hard use engines, the jury is still out of the detergent content. It seems high detergent oils, (HDEO) tend to wash cylinder walls down, preventing proper lubrication, and also, can wash away the boundary layer of anti wear additives, such as zinc/phos, moly, boron, etc. Racing oils which have quite high anti wear add packs, but little detergent, seem to have proven this fact out rather well. It seems in diesel engines the oil (with these higher detergent add packs) is pretty busy dealing with blowby and soot, and doesn't get to the point of washing away needed lubrication or boundary wear additives. It's quite and interesting supposition, that we, as Americans, have always adhered to the "more is better" theory, and here's yet another case it may not be true. Now, a lot of these oils are what are known as "mixed fleet" oils, and have spark ratings, but what exactly does that mean? The ILSAC rating for Xw30 oils limits the zinc (actually phos, but they're linked) content to something like
It would seem, at least from anecdotal data, that HDEO oils are doing just fine in air cooled engines, but could it just be that the manufacturers do know a thing or two about lubrication? I think we need to do some more reading. I'm not ready to go back to straight 30wt, or PCMO yet, but I'm interested in the theory.
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