We took this car to Car Max to get an offer for what they would pay for it. They gave us a low offer, 10K, stating that they heard "upper engine valve noise". The oil level is satisfactory on the dip stick. I do notice a constant, steady 'knocking' noise when it idles. Any ideas on how to get rid of the noise so we can proceed with selling it? It has 60K miles now.

They also lowered the price because they detected re-painting on the front end. It was done but only due to minor hail damage and a very shallow dent on the hood that was nearly undetectable; they said that didn't matter.

Thanks!

S80's of that year have a common problem with the oil pan pickup oring seals giving way and sucking air when the pump draws oil. You should see a airiated oil on the dipstick when you check immediately after turning the engine off. If it is this the oil pan has to be removed to fix.

Because they don't know the maintenance history of the car they are being understandably cautious. If the oil was changed every 3,000 miles it would be unusual to have a clattering valve train.

Also, since the body does have cosmetic damage they will knock the price down, just as you or I would if we were shopping for a car.

Edmunds.com would assign a trade-in value of between $10,000 and $12,000 depending on how condition is described.