The oil doesn't need to be 212° to rid itself of moisture, but it simply does so faster as the temp increases. I couldn't get mine to 212° anyway, especially in winter.

 

Oil doesn't need to get that hot to remove moisture. In an extreme case, even if your oil only got up to 150F, eventually after a long drive the moisture would be removed, it just takes longer to do it at a lower temperature. The hotter it gets, the faster it will evaporate, and as you mentioned, at 212F it will boil off. But even below that boiling point, the moisture will still evaporate.

edit- oops, I see that iclick already said exactly what I said

 

Except when starting, a journal bearing surface does not touch a crank main or rod journal. As long as there is oil present even the pressure in the galleries is not an issue as the hydrodynamic wedge formed creates high pressure that prevents metal to metal contact. Granted thinner oil means less pressure in the oil gallerias that is needed to handle pressure drops in the small passages but as long as it is suppling the volume the "wedge" pressure will exist! It's this high pressure that exists that allows an engine to live! Cold 90 weight oil could not provide the needed lubrication if the "wedge" did not exist!

PS: Unrelated to automotive lubrication, recall what was needed in welding wire drawing where the pressures are extremely high and even a grease would not work! Grease is an order of magnitude better than oil. Soap is an order of magnitude better than grease (that is why you roll a screw in a bar of soap and don't use oil!) The soap liquefies at the wire/die interface. Sodium stearate soap (Ivory) was less of a lubricate than a calcium stearate (Tide) - but hard to remove! Wire drawing soaps are actually mixtures that include fillers etc but look like powered laundry soaps!


Quoting the pics source: Automotive reciprocating engine bearings may have mean pressures of 3,000 to 5,000 psi. At these pressure levels, the viscosity may slightly increase. The maximum pressure encountered by the bearing is typically about twice the mean value, to a maximum of about 10,000 psi.

 

Which then leads to the question of "what's wrong with going full throttle/full rpm when the oil is cold?" I can think of several likely answers, but will refrain from speculating right now.

 

Here's my unscholarly take on this based on 50 years of pulling bits of info and shade-tree rumor from many sources, some of which may actually be valid. I don't think it has anything to do with the oil, at least once normal pressure is achieved very quickly after start up, but rather hardware tolerances. We have different types of metals of different configurations that don't get to normal operating temperatures (NOT) at the same rate. Thus one friction surface will heat up and expand more quickly than another--e.g., cylinder walls and pistons. When the motor is subjected to heavy stress it's better to have the components at the same states of expansion/contraction every time. It should also be stated that most wear on the engine is impacted at startup before oil pressure has stabilized throughout all components.

Once OT is at operating temp one can assume the engine and its components are there, too, as the metals transfer heat more quickly than fluids. Moreover, oil conducts more slowly than coolant, so OT is a better gauge, IMO. If you impose WOT on the car at varying conditions you are wearing the components more rapidly than if the engine temp is the same every time. All that said, it isn't wise to let the car warm up by idling. Rather, crank the car, drive off, and take it easy (when safe to do so) until NOT is achieved.

I invite comments and corrections from real engineers and other erudite sources.

 

IMO it's not the oil temp it's getting valve springs and other critical highly stressed parts warm! Toughness improves with temperature. In fact some heat treated steel is as brittle as glass at room temp! Valve springs are highly stressed. The surface "imperfections" that can cause failure grow quicker when cold.

Getting tolerances tighter like rings and pistons are also a factor. The large forged aluminum pistons in my 502 cid engine in my street rod sound like a sewing machine for a few minutes as they expand from combustion temps!

I don't think the 0 weight Mobil 1 is an issue by itself. My quick thoughts.

Answered before reading your reply.

We're saying the same thing!

 

Here is a useful chart.

As far as max temps go, with good oil the bearing temp starts to be a limiting factor rather than what the oil can tolerate. Note "bearings melt".

On the low end, I suspect with "contaminants not burned off" the oil doesn't protect the bearings as well.

 

That's an interesting chart(s). Do you think it's up to date with today's fluids, Mobil1 and auto trans fluids? I suppose it is but just asking the question.

 

Well, LDB gave a table with data on new oils. The results are not much different. If you get to 275F start slowing down. I suspect the mileage is if your running constantly at those temps and it is probably conservative.

 

I'm thinking that chart may be general guidance, but not absolute.
Our C6 (2009) oil was allowed to get to 302'F before the engine would give a "Hot oil- Idle Engine" warning, and at 320'F it would tell you to shut down and change the oil. I got the oil above 290'F on several sessions one day while having too much fun on a track, thought I might have damaged something but the next oil analysis showed that both the oil and the engine were doing fine. But I don't recommend that...