Normally engines get replaced on Audi's due to customer or tech error. I don't believe I have seen a 1.8t or 2.8 just get wore out. You can take a hundred thousand mile engine apart and the cylinder walls have hardly any wear. The 1.8t has a low oil pressure problem that has recently started surfacing. This is due to the oil capacity with filter only being 3.8 quarts. They have fixed this problem by adding a bigger oil filter that raises the capacity to 4.3 quarts. Also they recommend using synthetic oil to keep heat lower. If there is complete records on oil changes on the 1.8t it will be covered under warranty if you have a low oil pressure problem. So you would have to either make up receipts or if the previous owner has receipts then you have no worries.