Changing Gear Oil

I thought it would be a good idea to change the gear oil in the Xterra. I don’t know when it was last changed and it would do the Xterra good to have some fresh oil in its gearbox. Per recommendation from a coworker, I went to buy some synthetic gear oil for my transmission, transfer case, and the differentials.

At Autozone, I suffered a severe case of sticker shock. The combined oil capacity of the two differentials is 5 quarts, and the transmission and transfer case took 8 quarts, for a total of 13 quarts. The price of a quart of full synthetic gear oil, $9.99! And those were the cheaper ones! Others went as high as 15 to 20 bucks! Ridiculous! But my heart was set on full synthetic, so I bit the bullet and pulled the trigger.

Now, I knew sticky drain plugs would be a challenge, as it always is with these things. In theory, changing fluids is a simple task. Open the drain plug, drain existing fluids, close the drain plug, open the fill plug, fill in new fluids, and close the fill plug. But things are never that easy. Never. Except this time! I read online about which penetrating lubricant works best for loosening tough bolts. PB Blaster or WD-40 Penetrant? Neither. According to the internet, the best penetrating lubricant is a home made 50/50 cocktail of acetone and automatic transmission fluid. This will make my life easy.

Xterra Transmission-1722

With the car jacked up, giving me and James plenty of room to work underneath, I apply my home made penetrating lubricant. Mixing ATF (the lubricating agent) with acetone (the penetrating agent), how genius! Starting with the transmission, I crack open the filler plug with the help of a cheater bar. And guess what? The oil level is full, which means, no transmission oil leak! Yay! So… something else is leaking… probably the engine… (sigh).

It’s time to open the drain plug. I put some force on the plug with the wrench, nothing happens. That’s fine, the lubricant is probably working its way in the threads. I grab the cheater bar, but it’s too long. Not a problem, my dad’s probably got an extension somewhere. “James, can you find an extension for the wrench?”

Using an extension to attempt to loosen a stuck bolt DOES NOT WORK. I cranked on the wrench with extension and it all twisted at a weird angle and RUINED the drain plug. It didn’t quite round it out, but, the plug yielded and deformed.

Xterra Transmission-1724

I’m not sure how well you can see in the picture, but the four corners where force was applied are bent out of shape. Using an extension was a bad idea. It also didn’t help that the extension end was a looser fit than the wrench. Would be nice to have a breaker bar, to Home Depot we go. A breaker bar will give me the torque I need right where I need it, at the fastener head. After buying the breaker bar, we swing my Oreilly’s for a replacement drain plug. And surprise, surprise, I’d have to get it from Nissan. Just my luck.

Back in the garage, I put my new breaker bar on the plug and I give it a turn. NOPE! The breaker bar bit is at such a loose tolerance that it made my poor drain plug even worse. UGHHHH! This was supposed to be easy.

The Home Depot breaker bar has been returned and I’ll find a breaker bar with a tighter tolerance for another try at this tomorrow before the drain plug is completely ruined. Also, I’m gonna buy some PB Blaster.

To be continued..

Xterra Transmission-1733Update. Bought a Craftsman breaker bar (for $13!) and a bottle of PB Blaster. The breaker bar had a much tighter tolerance fit, but it was too late. The damage was already done. I gave up in the transmission and moved on to the other gearboxes. With the help of James and Ryan, we made easy work of changing the oil in the transfer case and the differentials. All the plugs came out easy with the breaker bar. Only if I had done this from the start, the transmission would be done. Though not a complete success, it was rewarding to have finished what I did. Another success was the ATF/acetone mix. All the plugs I got open, I opened using the mix, not a single drop of PB Blaster. I think it works.

As for the transmission, I’ll just take it to the shop and have them remove and replace the plug. Or maybe I’ll try extracting that plug somehow. It’s not a problem now, so I’ll worry about another day.

Xterra Transmission-1728

Update. We did it! With the help of my dad, we got the transmission drain bolt to break loose! My dad used a torch to heat the transmission case around the drain plug for some thermal expansion action. After a little encouragement from the breaker bar, the drain plug finally gave up its unhealthy attachment to the transmission. What a relief.

With the new drain plug in place, I pumped in the remaining gear oil and finally brought this job to an end. What makes this better is that I never have to do this again. The end.

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