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rotorwrench · 06-18-2021, 08:36 AM

Viscosity generally doesn't have much affect on the kind of pressure a pump can put out into the lube system but the clearances on bearings can show a difference with a different viscosity of oil. The more leakage around a set of bearings the less pressure can be built up. The differences aren't than much though as oil temperature increases.

These old engines need a lot less pressure at low rpm and under less load. They need the pressure under load and at higher rpm so I'd worry more about that than pressure at idle or low rpm. As long as it has some pressure it should be OK.

I use a calibrated direct reading gauge with a T fitting plumbed in to check my instrument readings.

06-18-2021, 08:36 AM	#15
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: Viscosity VS Pressure Viscosity generally doesn't have much affect on the kind of pressure a pump can put out into the lube system but the clearances on bearings can show a difference with a different viscosity of oil. The more leakage around a set of bearings the less pressure can be built up. The differences aren't than much though as oil temperature increases. These old engines need a lot less pressure at low rpm and under less load. They need the pressure under load and at higher rpm so I'd worry more about that than pressure at idle or low rpm. As long as it has some pressure it should be OK. I use a calibrated direct reading gauge with a T fitting plumbed in to check my instrument readings.