I would not run the engine with kerosene in the crankcase. One time I tried draining the oil and adding about 2 quts of varsol to disolve the buildup, then drained it after a day or so. It didnt work. I wonder if you could pull the distributor and run the oil pump backwards with a drill....feed it oil from where the filter screws on. Doing that after soaking the sceen with Solvent might flush it out if the pump will pump in reverse