You may want to take a look at the Hydrotex products... We used their teflon grease in our heavy equipment, on the pins. Great stuff..!! You could not beat it out of those pins. We ripped a lot of shale for fill, then loaded it on trucks. Many a day I've ripped, and loaded for 10 hrs. of operating time.
We did grease once a day, and never once had any problems. Just a couple shots per pin, and you knew you were good to go.
Two things to note about it though... When pulling the gun off a zerk, if you didn't have your rag over the end, it will "ribbon", and get on your clothes... Second, in the winter, we laid our grease guns in a box, on the passenger side floor, near the heater to keep it warm.. It pumps hard in the cold..!! Always tried to have a spare tube in the box too, keeping it warm.
I bought a box of 10 tubes myself to use around the farm. That's been 10 years ago, and still have 4 tubes left. That's how far it goes. Granted, it is just used on pins/hinge points, but lasts a long time..
Here is a link to a retailer/dealer search if you care to look.
Hydrotex® - Contact Us - Find a Represenitive
Maybe buy a box, and split it between your buddies, or maybe the dealer will sell you just a tube to try it.
Again..., it's not cheap, but sure lasts, and does the job..!!