GL 5 vs GL4 fluid
although the brand you used is fine, i surely hope what you installed is GL4 rated and not GL5. In short GL 5 is for rear ends and diffs that take a lot of load and heat. Gl4 is for transmissions with synchronizers that use yellow steel and soft steel. The GL 5 will destroy your synchronizers.

If GL5 is in the transmission, drive a minimum of 10 miles, pull into the garage and drain the oil out while hot! Replace with a 75w90 GL4 if that's what your transmission calls for.

Just mentioning the largest precautions and good luck!

 

Good point. I had forgotten my lesson years back on a Porsche 914 I owned the GL4 being nessary for the synco's.

The change WAS GL5. Yikes. Oh well I'll consider it a flush.

Come to think of it does Redline make 75w90 in GL4? The stuff ive seen is GL5.

Do i need to add a modifier to the "electric locker " rear end and will it mix with any type GL5?

 

Live and learn! How many miles has it been? I don't imagine long so not much harm has been done I don't believe. I'm quite certain after getting the fluid hot and draining it out you will get 95% of the fluid out as being hot it will flow out very fast. Don't need to make a special trip, maybe run to a part store, hardware store, do a regular errand then drive home and immediately drain.

Brand shouldn't matter really, but a name brand or known brand of GL4 75w90 can be purchased on Amazon. I went to napa and was shocked how much they wanted for non synthetic/ just conventional 75w90 (I never knew they made 75w90 that wasn't synthetic or synthetic blend!).

I imagine a fluid change will cure all issues as most people report after doing the same thing!

 

On your rear end oil question, I'm not sure what oil is required. If you lived local to here I would simply purchase the oil off your hands. But I imagine you could use the GL 5 75w90 in the front diff or sell/ give to a friend!

 

Now I see the fifth gear issue existed prior to the Trans oil change. Hopefully the new oil will help out the syncros! Definitely a very inexpensive thing to try first. Of course you can always double clutch to get in and out of fifth gear on your Tacoma. These don't have a clutch brake unlike a semi so it would be extremely easy to do! 😉

 

Thanks for the link I've been watching this guy covering everything Toyota. He really knows his stuff.

I sent a sample to blackstone oil for analysis, along with my usual engine oil, as I suspect the past owner may have changed the oil using GL5. The trans drained out looking fairly fresh relative to the black rear end oil.

My cheap non syn. fluid was experimental. The temporary oil change was originally in hope to eliminate the issue before going further into repair. The fresh oil decressed effort but didnt eliminate the issue.

After really becoming aware of the GL4 need, my next move is Red Line GL4 MT90 (75W90) for the trans, Lucas GL5 mt85w140 with LS modifier in the diff.
I may ad 25% Lucas stabilizer.? It claims better shifting which is my focus.

I'll post the results as soon as I get them.

 

Thanks for the link I've been watching this guy covering everything Toyota. He really knows his stuff.

I sent a sample to blackstone oil for analysis, along with my usual engine oil, as I suspect the past owner may have changed the oil using GL5. The trans drained out looking fairly fresh relative to the black rear end oil.

My cheap non syn. fluid was experimental. The temporary oil change was originally in hope to eliminate the issue before going further into repair. The fresh oil decressed effort but didnt eliminate the issue.

After really becoming aware of the GL4 need, my next move is Red Line GL4 MT90 (75W90) for the trans, Lucas GL5 mt85w140 with LS modifier in the diff.
I may ad 25% Lucas stabilizer.? It claims better shifting which is my focus.

I'll post the results as soon as I get them.

I've actually had people tell me the Lucas oil additive helped with shifting on newer transmissions. In your case maybe try the one Lucas came out with a few years ago. It's called "pure synthetic oil stabilizer." But either way it's good stuff. The 20 to 25 percent number would be plenty I imagine. At my part time job, I put 40 percent or so in the front drive axle and rear drive axles of a kenworth T800. The axle housing is cracked on the right side and supposed to get welded up, but actually it slowed down the leak a huge amount!

On bob is the oil guy, Lucas oil stabilizer was not recommended for engines at all, but has great properties for manual transmissions and rear ends.

 

Heres an interesting $15 trans upgrade.

Toyota Tacoma 6-Speed Manual Transmission Problems And Fixes

Toyota Tacoma is a very durable truck, and it rarely has mechanical issues; at least, less often than other trucks. If you're looking for the causes of your

vehiclefreak.com

Difficulty shifting in and out of gears also called a sticking shifter, is a problem experienced by almost all manual Tacoma owners. The problem only occurs after a long drive, like 500-1,000 miles, so it’s hard to replicate when you take your car to the dealer. Also, the problem is most prominent with the fourth, fifth, and sixth gears.
The issue is a straight factory defect that was worthy of a recall, but again because it was challenging to replicate, Toyota managed to avoid it. Luckily, the technically inclined owners and Toyota figured out the problem, and you can solve it for $15.
What causes this issue is a small ball head pin/plunger that sits right in front of the transmission oil filler plug. The only difference between the original and the revised part is that the new one has a flat side instead of being round. The revised part number is 33292-0K011, and you can replace it at home or have a repair shop do it, which won’t cost more than $50.

 

Oils changed. 5th gear much better but not 100%. I suppose the average guy may not even notice it most of the time. Seems to be when under quick shifting only, not normal shifting. Probably more characteristic to these transmissions than an actual issue?