I think that the 3 in 1 oil recommendation annually is for two reasons. It will inhibit rust in the staples, and it will create an element of lubrication so that the chassis twist will allow easier movement between the wings and the body tub. Like anything else, we have a choice and there will be consequences either way, but it will never be exact because both mileage covered, and the amount of wet weather encountered will affect the outcome.
If the movement chafes the paint, the aluminium will start to corrode.
