Lubricating rollers and hinges, tightening loose bolts on the track brackets, and testing the auto-reverse safety feature are all fine to do yourself, and they're worth doing every few months regardless of how old the door is. Clearing the photo-eye sensors of dust and checking the weatherstrip for gaps are the same story - low risk, real payoff.
What we don't recommend touching: the torsion spring itself. It's wound under enough tension to break a bone or worse, and that's true whether the spring is 5 years old or 20. On a door with a 1999-era build, the spring has likely been replaced at least once already by a previous owner or by us, and you often can't tell by looking whether it's near end of cycle life. If the door feels heavy to lift by hand with the opener disconnected, that's your sign to call rather than guess.