I have a 04 Passat 1.8 turbo w/ ~ 105K miles. I purchased it recently from someone who appears to have taken care of it. Assuming the engine is relatively clean, will adding Kreen to oil harm the engine and/or turbo? I've previously used Seafoam in oil on 3 different vehicles, but I can't say for certain if it helped clear up the gunk, it certainty didn't hurt anything, or may be there wasn't much sludge to begin with. My intention is to clean up the engine even if it has very little sludge build-up, but without the tedious 3k+ mile cleaning phase. I drive 5-7K a year max. To sum up my questions: 1. Is Kreen safe to use as a preemptive strike? (on clean-ish engine with little or no sludge) 2. Is it safe for the turbo? (1.8t audi/vw engine) 3. Does it call for specific oils to be mixed with? 4. How long is the recommended cleaning phase? FYI... I'll be pulling the valve cover tomorrow to replace the gaskets and will post a picture after.