Oil pressure light flickering sometimes

We use to run kerosine in gunked up engines and just let it idle for 10 minutes, drain, refill , change the filter and do it two or three times. That worked great for us. I have also filled a crank case with the original formula Hydra-Seal carb cleaner through the dip stick tube and let it sit over night. That worked wonders. of course we had to flush the pan several times afterwards before we put oil and filter on it.