I waterdipped a silver can once, in the kitchen sink with lots of water to keep it cool. After 5 battery packs there was no obvious wear to the brushes, man they are hard! More than five seconds with a Reedy, etc. will wear out the brushes, these lasted more than 50!
A friend suggested running in the motor until it is very hot, then dip the hot motor into ice water. The theory is the heat softens the copper wire and the sudden cooling will make the wire contract, resulting in tighter windings. Can't say it actually worked for my motor.
Still searching for that elusive "hot" silvercan motor
Tamiyamanuk, I believe you misread about oiling;
make sure that you put a drop of decent oil on each of the bushes
That would be the shaft bushings, use a fine sewing machine type of oil.