And I won't use Vaseline or any petroleum product on plastic or nylon. It has the potential to "eat" the gears depending on the make up of the gears. Synthetic only on plastic or nylon in my shop.
White called for Vaseline in their motors.
I'm guessing at your DH's plant - they knew what the gears were made of and definitely knew that the gears would not be compromised by a petroleum product. Since I don't have access to the actual make up of most gears, I don't take the chance.