I'd use a rubber /plastic compatible lube. WD40 is good for rusty bolts but it has solvents which will attack rubber and plastic parts. A buddy of mine had an old Ford with a creaky/squeaky front end. He started squirting WD40 on the suspension bushings every month. The squeaking stopped as the old bushings swelled under attack from the solvents but about six months later the car was all over the road because the bushings had totally disintegrated and fallen out!

Slim