In the past I used synthetic oil in my A4 from 6700 miles. I seem to recall reading here that switching to synthetic oil at higher mileage is not recommeded (my AR has 58k) due to the effects on gaskets and seals. I've searched here and at bobtheoilguy.com, but can't find the info again.

Any thoughts from the forum? I'd like to switch, but not if I'm better off with convential oil in the long run.

ill effects. I searched through BITOG before making my decision. It's been a while but the consensuses was it wouldn't cause problems. As always YMMV.

It used to be true that synthetics would leak more than conventioal oil, especially when high-mileage vehicles were switched over to syn. This was especially true with Mobil1 as it tended to run on the thin viscosity side anyway. But nowadays all synthetics, inluding Mobil1, contain additives to resist seal leakage in older vehicles. That's not to say any vehicle will not use more syn oil of a given weight than dino when changed over to syn at a high mileage. Just that the oil loss should be minimal. This has been discussed on BITOG, BTW.

Especially if you have the turbo motor, you're much better off with syn oil than conventional oil. These high-performance engines place high heat demands on an engine and require an oil that resists thermal breakdown. Conventional oil will coke up a turbo and may sludge up an engine (the 1.8t is especially prone to sludge).

Great synthetics that are VW 502.00-approved are Mobil1 0w40 & Castrol Syntec 0w30 (GC), available at AutoZone in the USA. Do a search on this board for more opinions & info.

I wouldn't hesitate. My local service manager (David at Jim Ellis Marietta) recommended the switch to Castrol Syntec every 5000 after 50K miles. My '01 2.7T is now at 70K and has had no issues.