Took my car to Mechanic A, a long established local garage with a good reputation for honesty. Have used them before and am very fond of them. They did a service which included checking the tres, the wheel hubs and the brakes.
They told me that one of my tyres needed replacing. They didn't have the right tyre (not really a tyre place) and advised me to get it replaced before I drove much further than home.
I took the car to Garage B. The guy, obviously a trainee, undid the nuts, changed the tyre, put the wheel back on the car, tried to tighten the nuts with the wrench and then called the others over, who all kind of huddled round and talking. As I went over I heard him who ask "But if you torque it up to 100 then you know it's OK whatever happens, don't you?" and the other mechanics saying "shh shh" and shaking their heads.
The boss came over and told me that my previous Mechanic must have used an airgun and damaged both the thread of two of the four nuts, and the hub itself. He said that the evidence of this was that there was liquid copper seal on all of the nuts. In the end he took out one of the nuts from my other wheel (solemnly pointing out the copper seal on those nuts too) and torqued them up so that now two of my wheels have 3 nuts out of 4.
I was inclined to think that Garage B did the damage rather than my previous mechanic because
(a) I do not believe that my mechanics would have let me drive away in a car with only two nuts fully torqued and the other two loose (if they were dishonest then i suppose they might have blamed the previous tyre changer) and I also think I would have heard the loose nuts rattling in the wheel.
(b) The kid unscrewed all of the nuts in the usual way - I saw him do it and none of them were loose, they all had to be fully unscrewed. It was only when he tried to put them back on that it happened.
(c) the torque setting for my car is 86, although I did not check that until afterwards, so if the kid had the wrench set to 100 then that was definitely too high.
(D) copper seal doesn't seem to be anything that would hold in a loose wheelnut?
However, before I kick up a fuss, I would quite like to know who to kick up a fuss with. Any ideas? Or can I just never prove it either way?