My thought as of now is this. Water/moisture is going to get in through the vent. If 4 wheel drive is rarely used it never reaches a temperature at which the moisture can be burned off so it accumulates. If I drive to work and back once a month in 4x4 it may provide enough use that this moisture cannot accumulate.
If a more knowledgeable person than myself can confirm or otherwise I would appreciate it greatly.

 

Well great I probably need to check mine. I've never drove through anything that would submerge it so I never thought anything of it. I do use my 4x4 on the beach occasionally though. I gotta check that though

 

DONT drive in 4wd on dry pavement! I have been told this can severely F^ up your rig

 

I've been told the same thing and have no idea why that would be true. Doesn't seem like it should affect anything differently other than tire wear to me. Anyone have any insight on how it can mess everything up?

 

In essence, when you turn, 4 wheels are turning at different speeds. When in 4WD, they want to turn at the same speed because they are all receiving power. This is fine when you are off road because the wheels are allowed to slip. However, this is not allowed to happen on the road, causing binding and stress on the 4WD system.

 

Ahhhhhh that makes sense. Thanks for clearing that up

 

Everyone's front diff fluid likely looks like there is some water in it... The front diff hardly gets used, so it doesn't make a whole lot of heat. The heat burns off the moisture that enters through condensation. That's why the rear diff fluid (which gets used every time you drive) always tends to look a lot better then the front diff fluid... Water can still enter either diff through the breather hose, so if you see sand and water in the diff, then its likely from submerging the the truck in water (which is a lot worse then condensation).

 

^ What he said.

4x4 is not the same as all wheel drive. Using the truck on other than "off road/pavement" in 4x4 is an invitation to more drive-line problems...

Going "under water" is another bugaboo, if you are not changinging fluids afterwards.