white/blue smoke

what happened with my 92 Geo Tracker was that one day I drove it to work and a little time later went out to get something out of the car and noticed it was leaking what I thought was oil.....so I had AAA tow it up to the shop by my house......well they steam cleaned the engin so they could see what was up......than low and behold the auto dude went to pull it into the shop and it died on him......they couldn't figure out what happened...I got pissed off at them and told them I wasn't paying for that as that was their doing and that was not why I took the car in in the first place.......anway they got it going but could never figure out what was up with the oil leak......so I have not been driving the car much since its been nice out and I have been driving a scooter I own......so about 3 days later we get in my Tracker for a drive but while going up a hill to get onto the freeway we see white/blue smoke comming out the back.....so I take the car back to the same shop and tell them what is up......they drive it around and can't get it to blow smoke.....figures.......so they are just guessing as to what it might be they say deep in the engin rings maybe......personaly I think they are full of crap because I
have been real good all these years with oil changes and what
not.....I'll be real surprised if it is that the engin is bad,,,,any
thoughts????