I inherited an 86 5 speed 2wd PU from my late father. Suspect the transmission and differential oil has not been looked at or changed. Is there a good link to how one can go about doing this? Any suggestions would be helpful.

 

Always make sure the fill plug comes out before draining any oil

If your in doubt just change it

When filling you fill to it starts coming out the hole.

When checking remove fill plug if oil comes out your good If it is just below and you can touch it with your index finger your good.

If it is really low you should see the leak some place.

 

I'll add:
- Get a cheap pump from Autozone that screws onto the jug of gear oil to pump it into the transmission/diff. Funnels don't work worth a bleep underneath the truck for this application.
- Use GL-5 for the diffs (easy to find) but try to get GL-4 for the tranny, assuming a manual. GL-4 is better for the synchronizers. Harder to find, though.

 

Just what wyoming9 mentioned above. In the picture below, on the far right, the yellow bolts are your drain and fill plugs. Same applies to your differentials, but seems to me the bolts are 20 mm bolts. I am going to look into the pump that RJR mentioned.I remove the shifter cover and use a funel with a long hose. (Clamps and can was a temp fix to get to the exhaust shop, I dont separate the Y pipe and manifold if it has a great seal, had removed tranny)

 

I'm not sure autozone carries these pumps anymore (??), but o'reilly's does. ww.oreillyauto.com/site/c/detail/PFM0/W1139/N0410.oap

Supposedly, you can use a funnel at the top of a long piece of tubing that's snaked from above to the filler hole. I can't imagine how you could do that with less than 2-3 people, though.

 

Sorry about your loss.

If you doubt if it had ever been replaced, I'd just go ahead, drain and replace using procedures mentioned^^

+1 for pump
++1 for making sure fill ports come out first before draining

That O'Reilly pump should work. No need for pressure, just need to push oil to level higher than fill ports. I just used a cheap bellows type pump from a 99-cent type Asian store.

Re: GL-4, I could only find it in synthetic like Redline MT-90. That's what I used on mine. Bought through Amazon.

 

Try a hardware store or farm supply store. Sta-Lube; I've used it since 1967. You don't need that expensive stuff...my $0.02

 

My diff has never been serviced in 190k miles. I saw the fluid cleanliness when I replaced a rear axle seal, and it was OK. I had to guesstimate to refill it through the vent bolt hole! Is it normal for the diff fluid to say in decent shape since there isn't much to get it dirty? What is the life of this fluid anyways?

When attempting to change the rear differential fluid (prior owner never did it 160k) the bolts were practically welded on. I did EVERYTHING get the bolts off to NO avail, and totally rounded off.
Ultimately I drilled a hole in the upper fill bolt trying to reverse-drill it out. No luck, as the drain/refill bolts are hollow and have cute little Magnets at the threaded-end tips. I believe they are 22mm. Ordered 2 new bolts and crush gaskets from Stealership at $20 for each set. I a shop literally use a blow-torch to weld on another bolt head to get the da%n things off. Fill with GL-5 and now I can do another drain/refill in a few months. I just hope that the fresh fluid doesn't cause some weird leak or problem that the old fluid was hiding .