Jeff,

I have coloured fuel using the food dyes that one would use in the kitchen when cooking cakes or colouring icing mixtures. Only a few drops are needed as the dyes are extrememly concerntrated. On the back of the packs there is a mixing guide so that any colour you require can be produced. Buy a pack containing the 3 primary colours & give it a go.

Once I mixed up some VERY red dyed fuel. Upon pulling the back off the engine after about 3 hrs use, I did note that the dye had lightly stained the internals of the engine (a bushed OS20) eg in the crankcase, on the crankshaft etc. But I dont see that as a problem - a wash out with kerosene & all was well.

Remember, only a few drops goes a long way