Bmw valves/ Piston rings

this is my first thread and im going to try to be as descriptive as possible any help helps !!! i have a 1997 m3, I was driving doing 100 mph accidently down shifted into 2nd gear... my car ideled for about 30 seconds and than died. I took it to a mechanic he said i probably had bent valves which i suspected... now hes trying to tell me he ran a compression test got nothing... put some oil in there and got some compression and now hes telling me its my piston rings and is trying to charge me quite a bit more. My question is if it was my piston rings wouldnt the compression still be low ????? Somthing just doesnt seem right to me... also when the car died it wouldnt start again and i thought with a piston problem it would still fire up but just run like crap... anything???

Find another mechanic. You money shifted. You probably bent all the exhaust valves and probably some of the intake. Bent valves don't seal, hence no compression. Adding oil may seal the valve and give some compression, but I really think he's trying to pull one off... If you were lucky, you didn't bang up the pistons too badly, and they may be saved. You have to take the head off anyway, then you will, (or mechanic will) see the real extent of the damage.

While you have the head of, might as well replace the seals and valve guides, (lifters aren't a bad idea, but expensive (24x $18 each))

They don't call it a money shift for nothing.

Then there is the reason you shifted into second when trying for forth. Check the transmission and engine mounts. along with the shifter carrier bushings, and change your shifting technique. See uuc motorwerks tech vedio on shifting technique.

If you didn't screw up the pistons just get a good head that already has the valves installed. Frankly the valves last a long time as do the seats and guides, 300K miles or more.
Find a good head, find a BMW mechanic not the guy you are dealing with and hope your pistons are not beat to hell.
Also expect to find some scoring on the cam journals and tray bearing caps. If the scoring is not to deep you can polish that out and replace the tray bearing caps.

As has been stated these engines don't respond well to revs over 7zk rpms.
Good luck and post what you end up doing....