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Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity

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The article may be want to say about Piston Varnish Merit Rating

as I know, it is CRC procedure, but i forget the procedure number
It is used to evaluate the varnsih which usually appear (buildup) at the oil-ring area (as well as the piston are) after a certain period of time.

Rating scale is defined in the scale of 1 - 10
10: for ecxellent, no varnish
1 : heavy varnished

so, for varnish merit rating, higher is better
Like all tests, one has to read the method and understand what the rating does.

More varnish is bad. But a scale assigned to clean vice varnishy can be anything. 1-10, 100-0, A-F, etc.

That statement applies ONLY to that test and in that context.

No good everyday application as far as I can see. I certainly can't get that info from a store shelf.

Although, I have extracted some decent info from manufacturers by asking to speak to the right people and talking backgrounds a little first. But not an everyday thing, and not always successful.

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