2002 Mini Base 237000 miles
 

I checked out a 2002 Mini base with 237000 miles for sale.It looked and drove like a new car.The only flaw was a rattle in the exhaust,when reving the engine.The bottom of the engine was pretty wet but not dripping any oil.It was pretty fast for a base car with 237k.It was a second owner,a 19yr old owned it for a year.He wants to buy a Civic SI with a 6spd.He was asking 3800 I offered him 3000 which he turned down.Called me a few days later said he would go down to $3500,I stuck with $3000.He doesn't have any records on the car.Am I crazy buying a mini with 237k.Any ideas what would cause the exhaust rattle.Also what other things should I be checking on the car.