Does it burn oil? People are noting that Valvoline Restore and Protect seems to clean the oil control rings and the piston drain holes.
Owned a 2001 330Ci couple for 17 years,
My humble advice: when you find a car that you're interested in, have it undergo a pre-purchase inspection by a reputable indie shop. If the seller refuses to have the car be inspected walk away.
I'd take the car to a reputable automotive AC shop. Have the tech refill the system with refrigerant with UV dye. When the AC stops working take the car to the shop and have them find and fix the leak. Then have the shop replace the dryer (it's 20 year old and likely shot) and perform a...