Larry, we use a spray can (2.5 oz) of 3 in 1 Lock Dry Lube. Any hardware store will have it. Most any brand will do. Imagine this: It also works good on the front door lock mechanism!
Jim and DW 49 years Brenda
2017 38rssa, also a 2015 Salem (for Alaska)
2019 F450, ruby red
Harley Road King & sidecar