Manual Transmission Fluid

[Aonghus]

I tried to pick up a gallon of Hy-gard yesterday and John Deere shop was closed. I'll get some tomorrow. 

 

I'm planning to try it my own commuter car, a 2000 Toyota Echo 5spd, before my son tries it in his first and only rig. Both vehicles have around 300K miles  

 

I'll update this thread with what we learn.

[adamzan]

On 3/7/2025 at 4:19 PM, Aonghus said:

Hey thanks that's helpful experience! 

We live in NE Oregon where temperatures vary considerably. We'll usually get over 100F in the summer for a bit and sub-0F in the winter for a bit. Coldest I've seen here is -22F and the hottest was 112F. There's usually several weeks in the winter when doesn't get above freezing at all. That factors into my consideration for a lighter weight transmission fluid. Whatever is in it now is notchy going into 2nd when it's cold in the morning.

 

I'll check out the specs for the Redline MTL and see what I can find.

 

EDIT: Redline MTL is 10.4cSt

That's great!

Sounds like your temps are close to what I experience. I don't drive my WD21 in the winter anymore because the salt killed my last one, but I drive a first gen Xterra with the same transmission. Sometimes I have to let it idle for 5-10 minutes just so the clutch fluid warms up from ambient engine heat, and the pedal isn't a marshmallow!

[FirstGenFreak]

I've done 15,000km on my reconditioned transmission using ATF dex III and had no issues.

The gent who recommended it has been building these gearboxes for decades.

I dismissed this at first and put 80w90 in it, then 75W/90, and couldn't select gears when cold.

Now it shifts great. 

Edited March 10 by FirstGenFreak

[Aonghus]

Thanks Adam and FirstGen, super helpful info. 

 

I'm gonna try this HyGard, picked up a gallon today for $33us. It's a touch lighter than the Redline MTL (9.4 vs 10.4) or about the same as the Pennzoil version of Synchromesh.

If it works great I'll stick with it. 

If it gives me grief in low temperatures I'll try the HyGard LowVis (7.4cSt I think) which is very close to most ATF options.

 

Not sure why I'm nervous about running ATF... I think just because they're both high mileage transmissions... But anyway I'm all about experimenting so we'll see! 

 

I'll update here when we have some miles on it.

[adamzan]

If it's made it this far... Either it was well cared for or replaced. it'll be fine

[Aonghus]

To follow through...

I put John Deere HyGard (standard, not Low-Vis) in my 2000 Toyota Echo this week and have done a little driving around town so far.

 

Initial impressions: it shifts really nice, the stick moves more freely in neutral, it *seems like the car accelerates a little more "freely." It's been quite warm this week but we're getting another cold snap so I'll get a chance to see how it feels on an actual cold morning. 

 

The oil I drained out of the transmission looked decent, it wasn't utterly filthy or runny or milky. I have no idea what fluid it was or when it was last changed to be honest. It was obviously much thicker than the HyGard but I didn't know if it was spec fluid or regular 90 weight or what. It was also low, drained out 56ozs and poured in 72ozs before it dribbled out the hole.

 

I've owned this little car for about 5 years and put over 40K miles on it so I'm pretty familiar with how it feels while driving in various conditions It's all seat-of-the-pants at this point but I'll say I'm pleased with how it feels.

 

My son is gonna try it his Pathfinder and I'll report back again. His is grindy going into 2nd when it's cold so that'll be a good test.

[Aonghus]

Update:

We replaced the old fluid in the 92 Pathfinder MT and put HyGard in a couple weeks ago. 

 

Drained and refilled using the full hole on a flat surface first. Then drove it up on ramps on the passenger side to tilt it far enough to get a the full 5.1L (5.4qt) in. And that worked! For future reference we needed about 10 inches of lift on the passenger side and it was just right. 

 

Similar to my little car, so far I'm impressed with HyGard. Much smoother on cold mornings (a few days in the mid 20s F) and most of the notchy feeling going into 2nd is gone. I've also noticed we can downshift into 1st while still rolling slowly, had to make a complete stop before. Again, it seems really smooth and *feels like it accelerates a little smoother or more freely. Overall a more pleasant driving/shifting experience.

 

With the old fluid (whatever it was), on cool mornings before moving, the idle would increase a fair amount when the clutch pedal was pushed in. That seemed to indicate a fair amount of resistance in the transmission when the clutch was engaged. Now I'm the same conditions the idle barely changes at all, almost imperceptibly. 

 

So far so good. We'll see how it does as the weather warms up. Being this fluid is used in massive tractors under heavy loads in the heat of summer I tend to think we'll be ok but it's also an unconventional use. The Toyota is easier to service so I plan to drain the HyGard and take a close look this summer and I'll give another update here.