Dv6 C-Max - Turbo Is Screwed

The other day, my dad bought a C-Max. It's 2004, 109,000-odd on the clock, TDCI DV6 engine. He pulled the turbo off the car to find that only one of the turbines spins. I've done a search around the 'net, and found out that this is a common issue, caused by a leaky injector, which causes carbon build ups, sludgy oil, which then gets into the turbo and knackers it.

Apparently, under warranty, they replaced the engine block "just to be sure" they'd gotten rid of all the carbon build ups. We aren't going to do that - too expensive and time consuming. But what is the best way to fix the issue? My dad was considering replacing the oil very regularly - every 100 miles, after the turbo is replaced, in the hopes that it will flush out all the deposits.

Has anyone here experienced this before, and what did you do to fix it? I had a cursory look around the forum and couldn't see anything on this, so forgive me if it's been posted before.

Cheers.

Milton.