I have a '00 Explorer xlt with about 80k on it. I recently just changed the oil on the front differential. It was gray(ish) in color and didn't have the best odor. I have never changed the oil in a differential before so this was new to me as far as sucking the oil out the fill port. My question is how often should this be done? Is there an easier way? I still have to do the rear differential. What color should the oil be?

thanks
Doug

 

Gear oil stinks. That's the nature of the product. It should be black or gray. It should not be brown or whitish, or have streaks in it (means water has got into it).

Assuming you have "automatic 4WD" (with a low range), and not AWD (without), the service interval for the front differential is basically "never". Most drives don't use the 4WD more than 10% of the time. When you are in 2WD mode, the ring and pinion do not spin. When you are in auto 4WD mode, there is no real load on the front differential unless the rear wheels are slipping. Just keep the fluid topped up, and change it only if you get it immersed in water (forded any deep rivers lately?). If you feel you must change the fluid, slurp it out -- it's way too hard to pull and reinstall the front cover, as I found out the hard way.

Ford's stated service interval for the rear axle is 100000 miles. In this case, you should pull off the rear cover and clean out any sludge/metal particles rather than slurping the fluid out with a suction gun. The rear cover is easily accessed. Use Ford's friction modifier additive if you have a limited slip rear axle. If you think gear oil stinks, wait until you get a whiff of the friction modifier. The local Ford parts counter man wrapped the bottle in three plastic bags when he sold it to me.