If you really are getting gasoline in your oil it will have serious consequences to the engine bearings,camshaft lobes, and all other mechanical components that are lubricated by crankcase oil. Oil cut with fuel just cannot lubricate adequetly.
You may have a leaky fuel injector dripping fuel into a cylinder, then past the rings into the crankcase when the engine is shutdown. This would not necessarily cause driveability problems or emissions. That diluted oil will sure as heck damage the internals though. Ask for a leakdown test on the fuel rail as a first troubleshooting check. Good luck