A door built around 1996 is old enough now that grease has dried out, rollers have flat-spotted, and factory lubrication on the torsion spring is long gone, but it's young enough that the opener is probably a chain or belt-drive unit with a circuit board, not the simple relay-switch openers from the 1970s stock you'll find in older parts of our territory. That distinction matters for what you can safely touch.
You can do the easy stuff yourself: wipe down the tracks, check that the photo-eye sensors near the floor are aligned and not caked with dust, and put a small amount of garage-door lubricant on the rollers and hinges, not the track itself. Twice a year is plenty.
What you shouldn't touch is the torsion spring above the door or anything involving the opener's force settings. A spring at or near 28 years old on a door this size holds enough tension to do real damage if it lets go while you're working on it. That's the one limitation worth saying plainly: DIY maintenance here stops at lubrication and visual checks, not adjustment.