In the older version of the game before it was tweaked to be mobile app friendly, there was a way to train your mechanics up to "level 20". They are now unable to be trained and I don't remember if their skill level is related to the old system of levels.
As a warning to anybody reading the forums, the overwhelming majority of posts over 9 months old may discuss expired information. The game is completely different right now to what it was before the update in August.
