I understand that WD-40 was NOT brought to market as a lubricant. The WD stands for "Water Displacing" so it is more of a penetrating oil than a lubricating oil.
It WILL free up parts, displace water, etc. but in my experience it doesn't hang around long enough to be a good lubricant.
'96 E300D 60k mi (wife's daily ride)
'95 Audi 90 118k mi (for sale)
'92 GMC Suburban 138k mi
'85 300SD 232k mi (my daily ride)