I'm thinking about selling my M5 that I've had for about 9 years - looking to get into something else.

It's got about 150K on it, but the tensioners have never been done. Everytime I ask my mechanic (who's very experienced in old M cars) about it, he says it's not making noise at startup, so in his opinion it doesn't need it.

Anyway, since the tensioner situation is pretty well known, I'm wondering if it would be worth it to have it done before I sell the car, or not - I'm concerned I'd even be able to sell the car at all without having it done.

Do you think I'd be able to recoup the investment (or get close, anyway) with a higher selling price?

Of course, what probably would happen is that I'd have the tensioner done, feel more confident about ringing the car out, and fall back in love with it, and not be able to sell it..