Dave, thanks for the info you sent.
Everyone,
I don't want things to get complicated by all sorts mixtures and potions and whatever have you, so I think I will just try a couple of standard thinners and the lighter fuel, all of which I have in stock.
Otherwise this will just end up like most of the posts on HMEM. Someone will give the right answer almost straight away, then everyone and his dog has to get in on the act and soon you get ten pages full of garbage, most of it just repeats of what has gone before. Ending up with someone who knows where to get it for 2 squid for 10,000 gallons, but the carriage runs into thousands, or you have to pick it up yourself from the oilfields in Outer Mongolia.
So thanks very much for your help everyone, it has all been noted and most will be tried until I get success.
John