I thought about oil temp, and suddenly realized I could check it easily with my thermocouple. It's calibrated for aviation use, even though it's a cheapie, so it's pretty accurate. It's 75 degrees out, I had been mowing for about 15 minutes. So, I did a quick check, prior to forgetting about it. I don't wonder why I've had engine failures with lower viscosity oils. 10W-30 just does not work for me down here.