I did an oil change on my old man's FG XR6 yesterday as it's been 18 months since it had been serviced at an independent mechanic.
I let it drain for half an hour while I had lunch. When I came back to my surprise there was only 5L of oil in the drain pan! The Barra is supposed to take 6.8L; surely it couldn't have burn 1.8L in 18 months? There's no sign of any leaks, which leads me to believe that the mechanic only put in 5L during the last service…
What sort of damage could this have caused? I took the car for a warm up and noticed there's a faint whine. 😕
Let's cut to the chase … the probability that you will have any claim whatsoever against the mechanic in question is bordering zero.