I assisted in a repair this weekend on Rubicon -- a guy had holed his oil pan, and was capturing the oil when we encountered him. I gave him props for being environmentally friendly, but that proved to be necessary, as well, since he lacked more than about a quart of bottled oil. He did have a few quarts of gear oil, but with the captured spilled oil, the most-of-a-quart of new oil, and about a quart of gear oil to get to the low point on the dipstick, he was good to go after the repair... which underlines why I like to pack a full oil change worth of motor, tranny, and diff oil (some may overlap, and simultaneous failure of all is unlikely, so some balance for weight/space/need is necessary).

I rank spares by necessity of repair... engine is critical, transmission less so (as long as it can turn in at least one speed), axles even less so (as long as at least some motion can be maintained), and so on.

Several tubes of gasket maker and brake cleaner saved the day for the guy on the trail -- having a propane torch to light damp wood to fire allowed a campfire which made waiting for the silicone to dry that much more tolerable!

Randii