STP - Worthwhile - charlie_boy
I have seen this adative by STP (correct if I am wrong) that you apply to a tank full of diesel. It is supposed to help cold starts, reduce emmisions and carbon deposits. Does it work on a diesel engine? Is it worth getting? Thirdly, it is a 1993 Astra 1.7TD Isuzu, will it harm the car?

Sorry for the 'thickness', but any help would be appreciated.
STP - Worthwhile - Dan G
I always put some additive in the tank of diesel on a regular basis to keep things clean. It improves starting and general performance, but it's effects don't last very long. They are also particularly useful to get a diesel through MOT emissions !
STP - Worthwhile - DavidHM
Apparently though the engine can become 'addicted' to it and it can (IIRC) accelerate valve wear. If the car needs it NOW, for instance if you're considering selling it, by all means use it a better long term solution would be a copy of Autotrader, a mug of coffee and a cordless phone...

Value my car