after noticing an oily smudge on the pipe work for the after-cooler where the rubber pipe fits over, I thought oh shit my turbo is on the way out and then had a look for a service kit on ebay. I asked a diesel mechanic mate about doing the turbo service myself and he said don't do it as he has seen a few amateurs stuff it up (he wasn't just spruiking for work). Also he pointed out the fact that the crank case breather is directed back into the suction side of the air supply, hence the oily smudge. I am thinking about doing the big clean up of the air supply on my 2.8 and am taking bits and pieces off this forum to work it out as well. another point my mate strongly made was make sure you thoroughly clean out any residual cleaning solution to avoid any damage down the line to the manifold, valves and pots.
