Not too much on the diagnostic advice (brain isnt all there right now), but if you are thinking of throwing a different turbo on it then you might need to get it tuned by a professional, unless you want to put countless hours into learning ME7 tuning and mapping out your bin. You will need VIDA to p...

The turbo will never spool up with the car sitting in the driveway. The car must be moving. Also the turbo is pretty unlikely to be the site of the oil/coolant mixing. Sounds like it could be fun to fix up! Keep in mind 99 is something of a mixed year and has quirks, it's the first year of ME7 engin...