This is a good read, and I’ve elaborated on some of the article’s listed items in the past (here, here, and here), but I’m not a mechanic nor do I claim to fully understand a combustion engine’s inner workings. This article comes directly from Viking Speed Shop.
While largely limited to the late model WRX and STI with the EJ255 and EJ257 motors, there’s been some concern raised about the sheer numbers of ringland failures being reported on the forums. Our goal with this article is to address why this is likely occurring and how you can guard yourself from it happening to your Subaru. Some of these may seem like common sense to most, but for many younger or first time turbo car owners it may be new.