oil for pump jack

[LoTec]

Greetings.
Anybody know what type/weight of oil is recommended to use in pump jacks? I still have a few customers who use them to back up their windmills when the wind doesn't blow. Around here (western Wisconsin) most of the pump jacks were made by the Duples company and have worm gears on a horizontal upper shaft driving the big gears, which are in line with each other, all in a cast iron gearbox. Most of them seem to have had 90 weight in them. However, given that most windmills used a much lighter oil (I use 10W non-detergent), I have theorized this is also appropriate for pump jacks. Anybody know?

[Wayne]

For what it's worth, I agree with you.

[Windcatcher530 Dan]

Yep you are correct !!

[windybob]

In a pump jack, thicker oil mayt not leak out shaft areas as much. Plus I don't think there are as many passages, or channels for the oil to go thru, it's just mostly splash or friction transfer.