After having a tin of diesel purge in my shed for over a year of putting this job off, I finally decided to crack on one evening using a guide on TDI Club. http://forums.tdiclub.com/showthread.php?p=823760 (Not sure if linking to other forums is accepted, please remove the link if so!) For ~£14 it is definitely a cheap maintenance/preventative measure that I'm glad I went through with. If anyone is familiar with a Terra/Carbon clean, I assume the process is somewhat the same - they hook up to your diesel lines and pump a liquid through your injectors. The benefit of this imo is that you can see the results AND it doesnt cost an arm and a leg! The process is pretty similar, buy some 5/16 inch or 8mm ID tubing, 1 straight hose connector, an inline filter to match and a glass jar. Disconnect your fuel lines going to the engine and connect these together using the connector which creates a loop back so your tank fuel circles from the tank to the filter and back round again. Connect up one of your new hoses to the return and put it in the jar, connect the inline filter to 2 lengths of the hose and then to the fuel line to the engine, making sure the filter is in the correct direction and with the other end at the bottom of the jar. Empty the liqui moly into the jar and run the car at varying revs until all of the liqui moly is used up - stopping before you reach the very bottom of the jar so you don't end up with air in the fuel lines! The benefits I noticed straight away were a quieter, less shaky idle and a smoother response from the car at low revs - the smoothness could be placebo but the engine is definitely quieter - wish I took a before and after video. Plus being able to see what came out of the injectors and got caught in the inline filter is satisfying to see. I also changed the fuel filter afterwards to ensure the system was only getting clean fuel afterwards. Here are some pics I took during The complete rig After ~2 minutes Almost at the end What was left in the jar Comparison of the old and new fuel filter and diesel - I cleaned the canister out after removing the diesel so it is now nice and shiny. The fact that my filter was so dark makes me wonder whether my injector seals are leaking and oil is getting into the fuel - will monitor and check my fuel filter after a few weeks to see if it has gone as black as before.