they tend to exagerate whatever "diagnosis" they tell you. i took my car to my dealer instead and they found that it was simplier than this shop's diagnosis. not only did they use the fear tactic on me -- telling me that it's dangerous to drive my car with its condition and that something needs to be done right away they also DID NOT tighten the oil cap which made the oil splatter and my engine work harder. if i did not pay attention to my engine's lost of power as i drove out of their garage i'm imagining that that would have messed up my engine... and no they did not seem sorry nor were they apologetic about it.
having said all that -- if you still wanna take your car to this shop, pay in cash... to say it in a more subtle way...