I put a few Mobil 1 API-SP oils into the HTFS/VII calculator. They don't provide HTHS in the PDS, but I can estimate it by adjusting it so that the base-oil viscosity index (BO VI) ~ 135.
That said, most API-SP Mobil 1 oils have a reduced VII content and a higher HTFS viscosity (high-temperature, full-shear viscosity = base-oil + additive-package viscosity at 150 ℃) than their API-SN counterparts. This is a good thing, as less VII results in a cleaner engine, and a higher HTFS results in less engine wear.
There was at least one exception. They increased the VII content and thinned down the base oil in Mobil 1 Extended-Performance (M1 EP) 0W-20 quite a bit, which is unfortunate because the API-SN/SN PLUS version was an excellent oil that was mostly PAO.
You can find the HTFS/VII table and the background behind it here:
That said, most API-SP Mobil 1 oils have a reduced VII content and a higher HTFS viscosity (high-temperature, full-shear viscosity = base-oil + additive-package viscosity at 150 ℃) than their API-SN counterparts. This is a good thing, as less VII results in a cleaner engine, and a higher HTFS results in less engine wear.
There was at least one exception. They increased the VII content and thinned down the base oil in Mobil 1 Extended-Performance (M1 EP) 0W-20 quite a bit, which is unfortunate because the API-SN/SN PLUS version was an excellent oil that was mostly PAO.
You can find the HTFS/VII table and the background behind it here:
HTFSV: High-temperature, full-shear viscosity
It is theorized that the wear for the following engine components depends on these variables among other things: Bearings: high-temperature, high-shear (HTHS) viscosity, TBN/TAN/base-oil oxidation performance (lead and copper corrosion) Piston rings: base-oil viscosity, TBN/TAN/base-oil...
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