Originally Posted by
ArchaicArcane
I should also mention that many "experts" say that a low melting point is important. Which makes sense because of what Mickey2 mentions - the motor axle/shaft doesn't get that hot. It also appears that there are at least 2 original formulations of the singer Lube. The UK lube has a significantly lower melting point than the US version.
I did the same experiments a few years ago, albeit no toaster oven. I was more concerned with the ability of the lube to migrate out, at room temperature, from the dab that was placed upon paper. This would be similar to the lube crawling from its reservoir up the felt wick and to the bearing. SM motors are seldom run enough to generate much heat, and the capillary action (wicking) of the lube continues even when the Sm is not being used. Lubriplate white greases and lithium greases are composed of oil that is absorbed by a metallic soap. While they have almost no melting point, the oil will wick away from the grease. My tests found that both Singer motor lube and Vaseline melted at around 115 to 120 deg. F., no other greases tested has so low a melting point...I have never seen a sm motor with bad bearings or a scored motor shaft due to lack of lubrication, but then again, I have only messed with a few hundred of them. What I most often correct is excessive end play of the motor shaft. Most grease reservoirs are found bone dry, yet there is no damage to the motor. Additionally, I have never found motor brushes short enough to need replacing. Johnm