For years I have been fighting occasional air loss; often I would have to pump it up every few days, sometimes every week or so. I tested it will soap (no bubbles except a few at the air valves) and sealed anything that looked like it might be worn.
Just a dab of glycerin in and around the valve seals has kept the air up for 45 days and counting. It is very slow to dry, perhaps several months in the open and slower in a valve. There is no potential to damage any of the seal or inflatable components. There is no mess; any spillage washes off. And there are certainly auxiliary uses in the medicine cabinet.
Why does it take so long to learn simple stuff?