I'm the 3rd owner of a 2002 A6 Quattro 3.0L V6 with 125k miles. Nice car in good shape. It was a trade-in. I have the service history and it has been well maintained. Even so, the CEL stays on except on longer road trips. Codes indicate low efficiency in one of the the cat converter banks. I was told that day to day I drive too slow and too little to heat the exhaust up and that I should hammer it into the higher RPMs every so often. There is a oil leak dripping onto something hot down near the firewall on the passenger side. Turbo o-ring? Cam chain tensioner gasket? Not much oil is consumed but it is worse after driving at higher RPMs. The same folks said not to worry too much about the burning oil smell or smoke, just keep the oil topped up. Thoughts? How many miles should I get out of one of these engines? Is it worth the cost to repair the leak on such an old car?