83 westy, 1.9 WBX. Last week it started smoking heavily out the tailpipe. I had just changed the oil and filter ( Castrol 20-50) and thought perhaps I had overfilled it. (4.5 litres). Dipstick said full. Not overfull.
I had also changed the engine compartment fuel lines using the Go-Westy kit just before this. I have inspected it all and there are no apparent leaks.
I have not driven it much since. I did do one 12KM return journey during which I added some fuel. I noticed then that the rate of fuel consumption seemed high according to the fuel gauge.

Yesterday I drove it again, noticed more blue smoke and returned home abandoning my errands. 
When I checked the oil level it was high. Over the full mark.
Today I drained the sump and filter. It came out in a rush despite the engine being cold.
There were over six litres of liquid, the colour of clean oil.
I put about 1/3 cup of it into an aluminum pie plate and brought a lit match to the edge. It immediately caught fire.
My conclusion is that somehow, I am getting gasoline into the sump .
Any suggestions as to how, why, or how to remedy this?
Thanks