Nissan Forum - Nissan Enthusiast Forums - Should I buy a used 2003 pathfinder 30,000 mi

My husband and I test drove a 2003 pathfinder today with only 30,000 miles and the dealer is asking for $18,000. However, my husband checked the oil while on the test drive and it was almost completly dry!! We couldn't believe it. We immediately went to the gas station and bought the oil that was suggested in the owner's manual and filled it. I just don't know what kind of damage this may cause in the future. We ran a carfax on this vehicle and it came back clean. The car is in MINT condition but there were no maintenance records. This truck/car was bought at auction by a friend of a friend and that is why we are going thru this particular person. Any suggestions would be extremely helpful. When we test drove the truck/car it seemed ok, to me a car is a car and just another payment.....but after reading a lot of postings I see that people are complaining of awful mpg as well as some other problems. Pls advise quickly. We are supposed to negotiate with the dealer tomorrow. Thanks!:)