I'm wondering what the life expectancy is for a turbo? I just had my 2003 WRX serviced in April and had a few things done including having an oil leak fixed. Two weeks ago I got an engine knock and I checked my oil level and it was 4 quarts low (oil light never came on). I took my car back to Subaru to look at and they told me the turbo was burned up and it had burned all the oil up and said that sludge kept the oil light from working. THey didn't say anything was wrong in April though. I have 130K miles on it. Does anyone know if this is normal? If it is, at what point should I start checking oil useage because I have another one with 90K miles on it and I don't want to have to go through this again.