Sounds like one of those 'you have a major prize waiting' gaffs!
Diesel fumigation eh??? I reckon it should be somewhere in a greenhouse but i expect one of the anoraks, sorry, tech buffs will come up with the answer!
I swear by the fuel additives that you pour into the fuel tank. they work wonders in my disco, cut the exhaust smoke down to almost nothing and it seems to help with the power output. IMHO anyway!!!