do you mean remove the tank completely?
...Long story mate, basicly, a work colleage asked me if i would be interested in some cheap diesel at 90p per litre. with the fuel prices continuosly going up...and further to go after xmas, I asked if it was ok and legal, he said he used it in his golf tdi with no probs and assured me it was legal. so I thought i'd try a barrel. I put 25 lites in two weeks ago and it ran fine, so last weekend I bought 3x 25l barrels off him....I put 2 barrels in on Sat morning...the car hasnt started since:-(. its now tuesday and I need to get my car running. I want to drain the tank and change the filter and refill with "proper" garage diesel. I cant move the car off the drive and the snow is about 8-9 inches. so the last thing i want to be doing in this weather is lying under my car but i guess thats the price i got to pay for doing such a stupid trick. I called my work colleage on sat and he had the same problem with his, but he managed to get his car coughing & spluttering to his mates garage to sort it. he appologised and said if i drain it back out he'l refund me.
I since checked on the tinternet and apparently cheap diesel has a lower cetane number. cetane level in diesel is like octane level in petrol. Its the measure of how quick the fuel ignites. modern diesels (especialy VW/Audi) require a higher cetane level.
I have learnt my lesson but now just want my car back to normal. :-(