Oil viscosity

dibbons said

I ran an Stewart Warner oil temperature gas in the bottom of the oil pan in a new (stock) 1971 383 Road Runner. The oil when warmed up ran hotter than 212 degrees, more like 240 degrees if I remember correctly.

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Good info to know. That's generally considered pretty hot for an oil - at least up here. I monitor the same way. Oil pan sump is the easiest location. My .060 over 340 ran up around 280 F on long highway runs at 70 mph. In part that was due to the external oil lines close to the exhaust. After removing those, it would run closer to 260 F. Still very hot; requiring more frequent oil changes and oil with good shear. It was fine at the drag strip or on local roads, more like 220 F. So I just never used it on a road course.

My current 340 runs cold. This weekend on the way to the dragstrip, it was 140-160 F on the local roads, 160 - 180 F on the interstate. Air temps were 40 F going to 50 F. Drag strip pass, or an autocross run will raise the temperature somewhere around 200 F.

Even on NJMP's road course this engine's oil wasn't over 220 F, although these were not even close to maximum effort laps. Going there, I did not know what to expect so brought two quarts of heavier grade oil in case the temperatures went higher.