I know, I know check the archive, but there seems to be alot of contradictory info. Just out of curiosity what oil weight are a4'ers using in the NYC metro area in a 1.8t. I plan on going with Mobil 1 tri synthetic i just want to get the right one. Dealer recomemded 10-40 one time and i called again to verify and someone told me 10-30. from what im reading in the archives poeple seem to be using 15-50. Mobil also recomends this on their website for turbo-charged cars. Any help would be appreciated.

99.5 1.8T

You can't go wrong with 10W40. I am in NC and run 15W50, I'll switch to 10W40 for the winter, but probably don't need to. Basically, the first number relates to operating temp, lower number for lower temps. The second number is the weight of the oil, basically how much protection it provides. All good motor oils in the weights specified by your manual will be fine.

Regards,
Rondey

'99 A4 1.8tqms

Several oil experts I've read and heard from (including expert techs, Mobil engineers, and Redline) caution against 10W40 because it has a much higher concentration of viscosity enhancers and other nonlubricating additives than either 10W30 or 20W50 (15W50 in Mobil's case). They advise using 10W30 or 15W50 and skipping over 10W40.