userfriendly
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I don't believe that VI is a driver in the fuel economy game, except during the first few minutes of warm up after a cold start at or near the engine oil's W grade.
If we apply 15W30 logic to PC-11/FA where the HTHS is between 2.9 and 3.2, I see no reason for 5W30 to be the go-to grade except to allow cold starts in winter conditions.
In fact, 2.9-3.0 HTHS is where Duron SAE20 is likely sitting, given the fact it is a high density mono-grade near the top of that grade's KV100C limit.
The problem of an XW20 FA-4 would be maintaining oil pressure high enough to provide enough volume to the piston squirters if the engine was designed for XW30.
Oil pressure in my experience follows bulk oil sump viscosity which reflects KV100C at operating temperature.
If we apply 15W30 logic to PC-11/FA where the HTHS is between 2.9 and 3.2, I see no reason for 5W30 to be the go-to grade except to allow cold starts in winter conditions.
In fact, 2.9-3.0 HTHS is where Duron SAE20 is likely sitting, given the fact it is a high density mono-grade near the top of that grade's KV100C limit.
The problem of an XW20 FA-4 would be maintaining oil pressure high enough to provide enough volume to the piston squirters if the engine was designed for XW30.
Oil pressure in my experience follows bulk oil sump viscosity which reflects KV100C at operating temperature.
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