My 15-year-old son pulled the defective Hella starter motor out of the 1987 Golf he's going to be driving in a few months. He's currently fixing up, or maybe breaking, the car. I ordered a new Bosch starter motor for him. Turns out my son thought the pinion shaft bearing looked dry. So he put grease on it. That did obviously not work because as soon as he let the pinion retract into the housing, the grease got wiped off. He didn't know that starter motors use usually sintered bearings that contain all the lubricant necessary throughout its useful service life. I do wonder if the residual grease that he put on may interfere with the lubricant in the sintered bushing. Am I being paranoid?