Grease is basically a base oil mixed with a carrier/soap. You use grease where you cannot physically hold oil to lubricate something.
For automotive applications, a Lithium Complex grease is the best all-around grease and it can withstand higher speeds and has a good drop-out temperature (temp at which the oil "drops" out of the carrier).
Certain greases can be mixed together, but just because they are the same color, doesn't mean you can mix them. Most of the colors are added by the manufacturer. There are tables online to show you what greases you can mix together.
"Sticky" grease is sometimes not always the best grease as it will make higher speed bearings run hot.
For example, at work we use two types of grease. One is a lithium complex grease which we use for everything (THOUSANDS of bearings) except one piece of machinery. This grease has an ISO 46. This means that the base oil is has a viscosity of 46 at 0 degrees C. The second grease is a high load grease that is only good up to 400 or so RPM. This grease has is an ISO 460 meaning the base oil is much heavier. This is a straight lithium grease.
That does hit everything.
Correction for you, lithium is not the lubricator in lithium grease. Lithium is merely mixed with the BASE OIL to provide better properties of adherence and dropping temperatures.
yep. Also likely why manual hub manuf. tell you not to fill your dials/innards with grease. Hub bearings fine.
I like the synthetic greases, either Valvoline or Mobil1. As Dave mentioned most any synthetic is good at resisting moisture intrustion. Synthetics also have a wider range of temps, so they work well in cold climates and on disc brake hub bearings. Plus I just go ahead and use this same grease for all Ujoints and all steering zerks.
back to the hub dials though, what works real well for those is Antiseize lubricant. I believe Sixlitre is a big fan of this as well for the hub dials being as he's from cold Canada. This lubricant (not sure I'd really classify this as a grease) has a huge temp range, stays put (does not wash out easily), but is not "sticky" as flourman describes grease. Try putting some on a warn hub dial inner lock mechanism once you've cleaned it all up. You should have a much easier time turning that dial, even in cold temps. Antiseize is also used when assembling stuff you know will rust over time.
You can also use white lithium grease on certain things. this is a grease, but unlike your "normal" grease you're used to using, this grease is much lighter. It will stay where it's put, and has some resistance to wash out, so for many apps is much better than picking up a can of wd40...uses might be door hinges to stop squeaking, wiper blade splined arm, squeaky leaf springs, etc.