jeff kushner
Full Access Members
Maybe John can answer MrS.... but most vehicle lubricants have not been engineered to land -40 in the curve of allowable temps. The question might be rephrased to "for those that don't warm up at -40, what are the failures?" Good question though.
The science at ultra-low temps is that loaded bearings, especially "insert bearings" suffer damage over time from the galling of the surfaces(metal transfer) due to a lack of lubrication providing the needed film. They try to minimize this from happening by using materials with higher surface tension. Still, the resulting damage will "loosen" an engine, as the engineered clearances extend. In many modern engine, reliance on high oil pressure and lots of insert bearings magnify the issue. Cams, crankshafts, rod big-ends....all the highest loaded bearings are now often "inserts".
Also, this occurs on heat-stripped cylinder walls when shutting off a really hot engine. The oil on the walls flashes off and w/i 8 hrs, rust is forming(believe it or not). Then, the owner starts the very cold engine, with oil that does not move for 40 seconds or so.... and he loads the engine by driving cold. While those oxides don't cause much deformation in the cyl walls, the oxides are now in your oil and too small to be captured by the filter.
Comparatively, gasoline is cheap.....jmho
jeff
The science at ultra-low temps is that loaded bearings, especially "insert bearings" suffer damage over time from the galling of the surfaces(metal transfer) due to a lack of lubrication providing the needed film. They try to minimize this from happening by using materials with higher surface tension. Still, the resulting damage will "loosen" an engine, as the engineered clearances extend. In many modern engine, reliance on high oil pressure and lots of insert bearings magnify the issue. Cams, crankshafts, rod big-ends....all the highest loaded bearings are now often "inserts".
Also, this occurs on heat-stripped cylinder walls when shutting off a really hot engine. The oil on the walls flashes off and w/i 8 hrs, rust is forming(believe it or not). Then, the owner starts the very cold engine, with oil that does not move for 40 seconds or so.... and he loads the engine by driving cold. While those oxides don't cause much deformation in the cyl walls, the oxides are now in your oil and too small to be captured by the filter.
Comparatively, gasoline is cheap.....jmho
jeff