MikeMarsUK
A2OC Donor
Bumped into this site which I've never seen before, looks interesting & I will have to have a proper browse through it on the weekend. They mention the engine-oil trick (near the end of the linked page).
http://www.dieselbob.co.uk/DieselFuel.aspx
http://www.dieselbob.co.uk/DieselFuel.aspx