While driving across Kansas my oil temperature was fluctuating from 203 up to 211. When I slowed down thru towns it would head down and slowly go back up at hi way speed. The coolant stayed at 180 and the tranny at 185. Is the oil temperature normal?
Larry
Yes. Near 220 is fine and boils water out of the oil .
Thanks Mike. I didn't think it was bad but I have never had an oil temperature readout.
Larry
You are good. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. Synthetics can take up to 450 degrees F. or higher (some as much as 700 degrees F). This makes it well suited for vehicles that are operated in hot climates as well as heavy-duty, turbocharged or hard-use applications.
Bill
Cummins told me that the oil temp thermostat opens at 225°F. on the ISM 11. Any temp under 225 is OK. Mine runs at right around 200 and under load (mountains) it will go up to 208-209.
Thanks. That is one less worry