[Classic30]

... Kero if used needs to be the highly refined grade.....

Knowing where Kerosene comes from, that's a very good point.. hence there's no way I'd even contemplate using store-bought kerosene for thinning paint.

Aside from the effects of the dye additive, there's likely to be trace quantities of water, particulates, 'diesel bug' and all kinds of other goodies in there that don't affect it's burning properties in the least but are very likely to affect the quality of your paintwork.