Put your hand on the shaft above your garage door at seven in the morning and it will often come away wet, on a day with a clear sky and a dry driveway. That is the whole problem in one sentence, and everything below follows from it. None of it needs tools you do not already own.
The mechanism, in plain terms
Airborne salt lands on every surface and dries into a thin film. That film is hygroscopic, meaning it pulls water vapor out of humid air and holds it against the metal, so hardware stays wet long after any rain has gone. The marine layer supplies the humidity, sitting over the coast overnight and burning off late, so the steel spends more hours damp than dry. On a part that bends thousands of times a year it matters more, because each little pit becomes a notch the metal has to flex across, and a notch is where a crack begins. An ugly hinge is one outcome, a spring retiring four years early is the other.
Rinsing, and how your address changes the interval
Plain water, no additives, no pressure washer. Take the hose without a nozzle and run it over the shaft and the spring coils above the opening, both bearing plates, every hinge, the roller stems where they enter the hinge, both bottom brackets, and the fasteners holding the track brackets to the wall. The aim is to wash salt off, not to clean anything. Frequency comes down to where you live. A few blocks from the water in Downtown, Townsite or South Oceanside, every two or three weeks is realistic. A mile back, monthly. East of El Camino Real, a few times a year covers it. Out in Morro Hills, Bonsall or Fallbrook this hardly applies.
Tracks get brushed, and they get brushed dry
The tracks are the exception to everything above. Brush them, do not spray them. A stiff hand brush along the channel then a vacuum is the whole job, and near the beach it wants doing every couple of months. Now why a lubricated track is worse than a dirty one. A track is not a bearing surface. The roller carries the load on its own bearing and only needs a clean smooth channel to run in. Put grease or oil in there and you have made flypaper: within a fortnight it holds fine sand, and sand suspended in grease is a lapping compound that scores the wheel and the channel together. If a previous owner greased yours, wipe it out with a dry rag and leave it bare.
What to lubricate, and what to leave alone
A lithium or silicone garage door spray, applied thinly and wiped back, belongs in these places: the hinge barrels where the pin turns, the roller stems, both end bearings, the center bearing, and a light film along the spring coils to slow corrosion. Leave these dry: the tracks, the photo eyes and their lenses, the plastic trolley, and the nylon roller wheels themselves. A rubber bottom seal prefers a silicone wipe to any oil. Then the most common mistake made in a garage. WD-40 is a solvent. It frees a seized bolt and it is the wrong thing to leave behind as a lubricant, because it thins and takes the grease with it.
Twice a year is the coastal interval
Inland an annual service is fine. Within a mile of the Pacific, twice a year is the honest answer, and the reason is that the damage runs on a timetable you cannot see from the driveway. A tune-up at an estimated $89 to $165 covers balance, fastener torque, roller and cable condition, sensor alignment, opener force and travel, and lubrication. Two of those a year against one broken spring and the opener repair that often follows it is not a close call. Rentals are a question of timing rather than frequency. On a let near the Harbor, or a home around Camp Pendleton changing hands at PCS turnover, book it at the changeover while the garage is empty.
The two minute balance test
Once a season, and it beats any amount of looking. Close the door, pull the release cord so the opener is out of the picture, then lift the door by hand to about waist height and let go. Balanced, it stays put within a couple of inches. If it sinks, the springs have lost tension. If it climbs, they are wound too tight. Either way the opener, the rollers and the top brackets are carrying weight that was never theirs, and openers that die young on this coast usually die of that rather than anything electrical. Reconnect and run one full cycle afterwards.
Three parts stay off the maintenance list
The wound torsion spring, either lift cable, and the bottom bracket at each bottom corner. The spring holds all of its stored energy with the door shut on the floor. The cables are the only route that energy takes into the door. The bottom bracket is the anchor the loaded cable pulls against, so undoing its bolts with the door down hands you the lot at once. Look at those parts, hose them, note anything fuzzy or flattened, and give the spanner work to somebody who does it daily. Everything else here is fair game for a homeowner with a brush and a hose.