2002 Chevy Impala gas smell in oil

One week after having my oil changed, (3 months ago) the low oil pressure light came on- (constant flashing) I went right to a service station, added one quart. It was low. A few days later the light came on again. Stopped, checked level. It was well above the line. A mechanic friend told me to smell it, which I did and it smelled like gasoline. He suggested I get a oil change asap.I did that night, and took it to a repair shop the next day. The evidence was gone. No smell, another crazy lady. Yesterday, 12/31 -(2 1/2 months later), the same light came on (no flashing however) I checked it- it was 1 quart low and the gasoline smell was back. There was also a goldish colored gunky substance on the inside of the cap. Which also smelled gassy. What's up?