Retuning the motor won't gain you much for how much you will be charged, it's not a turbo motor or even a good na one. Sludge is more of a 1.8t problem because they used to small of an oil pan with non syn oil and long change intervals. The 2.8's don't seem to have the problem. I did drop my lower pan anyways and checked and the pickup was clean at 130k miles. Takes maybe 20's to remove and reinstall the pan.