It’s a good idea to change out the oil in the front and rear differentials periodically. Hard to say how often, once every 3 years or so. Some might say every 15K miles. Certainly need to more often on an old truck like an ’83 K5 Blazer. This is preventative maintenance. The differential is also known as the pumpkin because of its’ shape. Most cars and trucks have one on the back and one of the front (if 4×4). The diff takes power from the drive shaft spinning and uses gears to transfer that motion to the axles that spin the tires.
In this video, I walk through a full cycle of draining the oil from both diffs, removing the covers, cleaning the diff innards, putting it back together and filling with fresh oil. I also show how I overcame a particularly difficult problem: rear diff fill plug was stuck and stripped. Then it got worse when an easy out snapped off inside the plug. I couldn’t drill through the easy out, even with cobalt and titanium drill bits. Irvin bolt-grip did the trick and I was back in business.
I have an old 1983 Chevrolet K5 Blazer, my project truck. It has a 5.7L 350 engine, lift, back country shocks, 33 inch mud tires, custom paint, custom seats back and front, and more new parts under the hood than old. I’ve replaced the transfer case, radiator, brakes, alternator, rebuilt tranny (shopped this one out), brake booster and more.
I like do repairs on it and this is one of my hobbies. I’ve started video taping my projects to be educational for others with a similar hobby. It’s also a payback for all the great videos, blogs and forums that coached me through.