Doug,
The Mercedes 228.x specifications are on p.46 of
http://www.w124performance.com/docs/general/oil_rating_info.pdf
You can see that for all 3 tests 228.5 is more stringent than 228.1,3 on "piston cleanliness".
Virtually every oil on the 228.5 list is Grp.III, with 2 or 3 Grp.IV. If we could agree that Grp.III is synthetic (?!?), then is this correlation coincidence?
Of course this does not prove a causal relationship. And piston dome cleanliness is not ring groove deposits. But both relate to exposure of oil to extreme conditions.
Charlie
The Mercedes 228.x specifications are on p.46 of
http://www.w124performance.com/docs/general/oil_rating_info.pdf
You can see that for all 3 tests 228.5 is more stringent than 228.1,3 on "piston cleanliness".
Virtually every oil on the 228.5 list is Grp.III, with 2 or 3 Grp.IV. If we could agree that Grp.III is synthetic (?!?), then is this correlation coincidence?
Of course this does not prove a causal relationship. And piston dome cleanliness is not ring groove deposits. But both relate to exposure of oil to extreme conditions.
Charlie
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