I have a 1988 22R 2WD with a 5-speed manual transmission fluid. The daily payload is 1000 lbs on short haul trips, flat ground, 30-60 mph cruising speed, in-town stop and go driving. Fairly new clutch.

My question is, does anyone check or change the transmission fluid in these trucks? I have never heard of anyone checking or changing the fluid in a manual transmission, but the book says change as much as every 15K miles.

I have already changed the fluid in the differential case (because it was out of the vehicle, so why not?)

Don't know if it's even possible for me to change the fluid as I have no way to reliably refill the transmission. Looks like a pump is required to get the fluid in there.

 

You Tube might have the perfect answer to my question:
If anyone has anything else to add I'd be glad to hear it.

 

I pretty much change the fluids when I get a new vehicle .

Then I check the level around every 6 months

On my Work truck all the fluid in the gear boxes gets changed once a year then that is 30 to 40 thousand miles

 

Same as Wyoming. I always drain, fill with cheapo for a few hundred, and then drain and refill with whatever name brand is on sale (except Pennzoil)

 

Why would you not change a fluid?
its basic vehicle maintenance
I refill manuals from the top.
pull the rubber boot back from the shift lever and fill until it comes out the fill plug on the side of the transmission

 

dropzone beat me to the punch, its way easier to fill from the top for sure, especially the 2wds. I check my transmission and transfer case every summer, no matter the mileage.

 

Yes, like this^^^
I drained and replaced all when I bought the truck in 2012.
I use conventional oil in differentials.
I use synthetic Redline GL-4 MT-90 in the transmission and the transfer case, because:
1) There are doubts abut using GL-5 in transmission,
2) Tranny and transfer case are near the engine so they are hotter and synthetics take more abuse to breakdown.
However, I don't know what transmission shop used to re-fill after tranny was rebuilt.

My truck is not used under extreme conditions, so I only inspect and top off if necessary IAW FSM. If found with lots of metal particles or not clear anymore, I would replace.

My question for you guys:
IF necessary to drain gear oil (although gear oil does not need replacement, like when doing rear wheel bearings), would you reuse if still in good condition?
For environmental and economic reasons, when I do my rear wheel bearings, I plan to collect gear oil in clean container, strain with lint-free cleanroom wipe cloth and reuse.

 

I would say it really depends on how many miles or how much time is on the gear oil. If the gear oil has been in the transmission or differential for a long time or many miles, to me it would be a no-brainer to just replace the gear oil. Unless the gear oil is just awful and full of contamination, it is difficult to determine if the gear oil is in "good" condition.

On the other hand, if you had recently replaced the gear oil and there was not a catastrophic failure (i.e. metal particles in the gear oil), then it would probably be fine to reuse. Like engine oil, I suspect that gear oil has additive packages that break down over time and use.

To me, it would make more sense err on the side of caution and replace the gear oil. Typically it is cheaper, easier, and less time consuming to simply replace the gear oil than having to replace the parts that could fail when not properly protected by potentially old (additives no longer function properly), dirty, or contaminated gear oil.

 

When doing wheel bearings, do one side at a time. Only jack up the side you're working on. This will cause the gear oil to all flow towards the other side. No need to drain anything.

 

All helpful comments. Thank you.

I have one to add: Initially upon removal the drain plug didn't look dirty, just smooth and a little slimy. But I dug deep into the top of the plug with a screwdriver to reveal a magnet, and the slime that I carved from it is actually fine metal shavings scavenged from the fluid. When the plug is clean, you can clearly see the magnet and you have to clean the recess around the magnet to get all the shavings out of it. This step is not mentioned in the You Tube video.

If you are only used to working on cars from the late 60s and early 70s (as I was), you might not know that nowadays drain plugs are magnetic, and you might not know to clean them out.