Mine makes oil. Put Mobil 1 in 3k miles ago. Checked the dipstick and it was right at the top. Checked it today and it was past the full line. My gas gauge is not like that.

Rick

 

Maybe your gas is getting into the oil? Also, if you check your oil after you've been driving, it'll be lower than if you check it after it's been sitting for a while. The slope of the vehicle when you check it can also affect what you see on the dipstick.