I have also had this occur in the hydraulic oil of an agricultural tractor.
Yeah, it's not advisable to operate your tractor IMC...
Having the oil temperature "in the green" is, of course, perfectly fine for flying, but may not be ideal for boiling water out of the engine oil. I flew both of my planes yesterday, as neither had moved in a few weeks. My Lycoming O-360 had a cruising oil temperature stabilized at 143F - not enough for my liking. So, in an effort to heat it up (without landing to put on the oil cooler baffle), I hung the plane off the prop at a higher power, with the stall horn bleating, for about 15 minutes. Doing so got the oil temperature up to 157F. Still not hot enough to boil water off, but, a start. It's winter baffle time here in Canada now - today's little job!