White = water, so replacing turbo oil seals probably won't help much.
Have you removed the turbo to see if the water jacket has cracked? Water is helpful as it cleans as it leaks (like a steam cleaner) so upstream of the leak should be the usual sooty mess, downstream should be clean.
To check the water jacket on the turbo the easy way- remove the water lines to it, and take the car for a drive (no prolonged boosting) if there's no steam, there's your problem. If there is, then it's not you turbo leaking water.