The 1.8T engine is listed as one of the engines that has a problem with sludge accumulation.
What is sludge?
Oil sludge or
black sludge is a
solid or
gel in
motor oil caused by the oil gelling or solidifying, usually at temperatures lower than 100 degrees
Celsius. Sludge can be a major contributor to
engine problems, and can require the engine to be replaced if the damage is severe. Sludge is usually caused by the presence of
water in the oil, and can accumulate with use.
Sludge can be countered...Frequent oil changes (every 3k miles is now the general rule, however in the average engine it's really only needed every 6k) So, more frequent oil changes, KEEP UP ROUTINE MAINTNENCE (normally listed in your manual), using synthetic oils also helps.