Valvoline VR-1 vs. Lucas Hot Rod oil
His graph using typical SAE specs. I've added the Farenheight
Next is a closer look at the operating temperature range.
The 'zone of protection' is a reference to his text that this goes with. That zone is the viscosity range that best supports the bearings, carry away the right amount of heat, etc. in an air cooled flat six. But all of our engines had very similar oil requirements, although a little wider range.
This is why I wrote that an engine that had good pressure and flow with a 10W-30 or a 5W-30 at the drag strip might need a 10W-40 or 20W-50 pulling a trailer or in an endurance race. In those situations coolant temperatures may be only in the 200 - 220 range because of the high airflow, while oil temps may be much higher.
Exactly. Widman illustrates that with his graphs of Viscosity vs. Temperature.
His graph using typical SAE specs. I've added the Farenheight
Next is a closer look at the operating temperature range.
The 'zone of protection' is a reference to his text that this goes with. That zone is the viscosity range that best supports the bearings, carry away the right amount of heat, etc. in an air cooled flat six. But all of our engines had very similar oil requirements, although a little wider range.
This is why I wrote that an engine that had good pressure and flow with a 10W-30 or a 5W-30 at the drag strip might need a 10W-40 or 20W-50 pulling a trailer or in an endurance race. In those situations coolant temperatures may be only in the 200 - 220 range because of the high airflow, while oil temps may be much higher.
