A mechanic at sears auto center told me I had a oil pan leak. But i have not seen any oil leak from under my car. He recommende

When I first bought my Malibu, I took it to sears auto center to hand it looked at. I had a loose tire rod and he said an oil pan leak. I got the tire rod fixed but the oil pan together was too much. He said it'll be fine if I just keep oil in it. So I haven't gotten my oil changed in 3 years now. I've never seen any oil leak and I've only come to grips of my incompetence. Why didn't I check or have it inspected to verify. I want to know the dire consequences of not changing my oil.
My car has an automatic transmission.

– A mechanic at sears auto center told me I had a oil pan leak. But i have not seen any oil leak from under my car. He recommende