superspark wrote:

There are several good fuel additives on the market which you can add yourself to help desolve carbon deposites such as redex.

Yep, you're absolutely right, but these additives (like the 2T oil), by raising the cetane number of the diesel fuel, will help disolve the carbon deposits from inside the combustion chamber...
And where do you think that carbon deposits will go? Down the exhaust manifold....
And where do you think the turbo's input impeller is? First thing after the exhaust valves, down the exhaust manifold...
So the problem of turbo's contamination with exhaust byproducts is still there...
Therefore, a good old fashioned italian tune-up is good from time to time to purge the exhaust manifold.

ok mate thanks ive got the diesel car Chris Binns