LOL, I like that!Only a cold start on the surface of Mercury or Venus during the day, but you'd need at least a -200W for the early mornings.
There's a problem at start-up that the OP has chosen to ignore over the last (20???) years ?No oil is too thin on start up ?
I know, it and know it well.There's a problem at start-up that the OP has chosen to ignore over the last (20???) years ?
Cold engines rely on the hydrodynamics of thick oils to keep the parts separated....the primary wear time is the point at which the oil is thnning, and the additives aren't fully functional with heat.
The sequence IVA wear test specifically holds the oil at this sub optimal temperature, where hydrodynamics is poor, and additive function is too, to accelerate the wear by orders of magnitude.
This has been confirmed by at least three oil formulators (some of who worked for the majors), and are familiar with the test regimes, and what they are designed to do.
Regarding question 4 where people say thickening is never the problem:
Evaluation of Oil Performance Using the Tu High Temperature Engine Test With a View to Extending Oil Drain Intervals, Bouvier et al:
Oxidation and thickening is the limiting factor for oil longevity. Generally modern oils thin only 10 percent then thicken up to 60 percent within as little as 96 hrs. of operation ( -in the accelerated test engine. Let me comment that all test criteria are designed to mimic real engine operating conditions but at an accelerated rate).
There is accelerated acidification and corrosive wear that occurs.
Oil thickening was also time dependent. Thickening at 30,000 km was 2 times more when done over 21 months than over a 10 month period. (Change your oil every spring as I suggested before).
Journal bearings seem to be less sensitive to lower HTHS than other moving parts in an ICE because of their full hydrodynamic lubrication characteristics. For parts more susceptible to rub together due to low HTHS viscosity with thinner oils, those oils will typically have more AW/AF additives to mitigate wear (ie, giving more "film strength") when the MOFT goes to zero.Food for thought:
In our laboratory, it has been observed that in a modern gasoline engine, well designed automotive bearings can be lubricated with oils as thin as [HT/HS] 2.3 mPa.s [or cP] WITHOUT ANY (my emphasis) observable wear on either con-rod or main bearings.