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As it’s winter....
https://www.blackstone-labs.com/wp-c...Aug-17-ENG.pdf
“ For wear metals, though, there’s not nearly as much variation. Iron is between 8 and 11 ppm all across the page, and copper is between 7 and 12 ppm for each set of averages. Other metals had even less variation, and no single oil type had the lowest level of all metals.
So what does this tell us? Well, on the face of it, it doesn’t really look like the levels of additives have an awful lot to do with engine wear. Brands with more calcium and zinc don’t have significantly better wear readings than the brands with relatively lower additive levels. The Rotella T6 does seem to have a slight edge, since all metals are reading at the low end of the spectrum, while the Subaru 5W/30 has some of the highest levels, but the margin is pretty thin.
Breaking it down even further, we can look at the level of iron produced by engines running each type of oil on a per-mile basis. Iron is from steel parts, so it’s the dominant metal in most engines, and it tends to track with oil use more than the other metals do, so it makes sense to look at the wear- rate, or the amount of iron per mile.
Shell Rotella T6 had the lowest iron wear rate, at 2.03 ppm per 1,000 miles, while Royal Purple 5W/30 had the highest wear rate, at 2.58 ppm per 1,000 miles. The difference is just over half a part per million per 1,000 miles, which is almost completely negligible.
In a typical engine, a half a part per million of the oil in the sump is such a small quantity that you wouldn’t be able to see it without a microscope. To put that in perspective, an Olympic-sized swimming pool holds about 660,000 gallons of water. One half part per million of that volume would equal just over 5 cups of water – that’s like mixing half of a 2-liter bottle of Sprite into the pool, and it makes about as much impact on your engine: if you know it’s there, it might bother yOu....”