94 pathfinder MTF info

[Honeybadger]

So I did a big fluid day (coolant, engine, rear diff, tranny) yesterday, and used castrol hypoy C 80w90 (MT5, synthetic blend) for the tranny and my diffs. The diff is happy again, but my transmission now feels like it came off of a tractor. Very notchy, when it's cold I am almost catching the synchro in second off guard (never had transmission issues before the fluid change)

Did I use too heavy a weight for Seattle driving? The shop ran out of Hypoy C in 80w90, so I had to mix in a quart of valvoline synthetic blend 80w90. Could this be the culprit? Could it be that I used MT5 instead of MT4? Should I really drop the coin on synthetic, and does it make that large of a difference in tranny feel? This is just my truck, not a race car, so I've always used mid grade products with it and just kept on top of maintenance.

The truck has a capacity of 7 quarts, but using the drainplug only evacuates 4. If I need to get rid of what I put in or change the weight (previous weight/make that I mixed the new stuff in with is unknown) should I just drop the pan and do the filter/gasket while I'm at it? or just do a couple more flushes over this month to get things mostly right?

 

[Towncivilian]

You need to overfill your transmission (assuming you have a 4WD here) - there is a TSB for this. The fill plug is 0.97 inches too low. Read here.

I don't know where you read that it has a capacity of 7 quarts. See page MA-8 of the factory service manual - all MTF capacities are listed in pints.

You also must use GL-4 MTF. GL-5 will harm the transmission. Amsoil MTG and Redline MT-90 are excellent options.

Welcome to BITOG!

 

[Honeybadger]

that 7 I heard must be pints. that's reassuring (I do have 4wd.) I'll go get working. Thanks!

 

[stephen9666]

I think 1990s Nissans have very sensitive transmissions. My 99 Frontier shifts very poorly with anything but the factory fluid. I tried Amsoil, Royal Purple and plain old gear oil and the shifts were all worse than the factory fluid.

Check with Nissan. I usually pay around $9 - $12/quart, but it's worth it to me because it works the best.

 

[Honeybadger]

Just put in some 75-90 amsoil synthetic GL-4, overfilled from 3.6 to 5 quarts through the gearshift tunnel.

Back to shifting like butter! Glad I fixed that after only driving on it for a morning.

 

[Towncivilian]

Great! Glad to hear everything's back to normal.

 

[mechtech2]

You put gear oil in a manual trans.
Shifting will be compromised.
Unless they are shooting at me and I have to get away, I would use a dedicated manual trans fluid, for sure. Amsoil and Redline have superb offerings in different viscosities.

 

[Honeybadger]

Originally Posted By: mechtech2
You put gear oil in a manual trans.
Shifting will be compromised.
Unless they are shooting at me and I have to get away, I would use a dedicated manual trans fluid, for sure. Amsoil and Redline have superb offerings in different viscosities.


That's what manual transmissions have. Gears. The weight is the same, and the GL-5 oil is designed for transmissions as well. I've run GL-5 in lots of other transmissions for 100k+ miles and never had a problem.

But a few manufacturers just need the GL-4. It's so uncommon that you need to actually do some looking to find the GL-4, and most dealerships carry only GL-5 on the shelves, while the GL-4 stays in drums in the back for the specific applications required.

 

[aquariuscsm]

Originally Posted By: stephen9666
I think 1990s Nissans have very sensitive transmissions.


They really do! Mine would crunch 1>2 with anything except Amsoil MTG. Best manual tranny fluid hands down!

 

[rpn453]

Originally Posted By: Honeybadger
That's what manual transmissions have. Gears. The weight is the same, and the GL-5 oil is designed for transmissions as well. I've run GL-5 in lots of other transmissions for 100k+ miles and never had a problem.

But a few manufacturers just need the GL-4. It's so uncommon that you need to actually do some looking to find the GL-4, and most dealerships carry only GL-5 on the shelves, while the GL-4 stays in drums in the back for the specific applications required.


It is weird how hard it is to find GL-4 MTF compared to most other automotive fluids. I don't know of any synchronized manual transmissions where I would be inclined to use a GL-5, even if some say that it's acceptable. Which ones have you had success with using a GL-5?

Welcome to the forum!

 

[Honeybadger]

Originally Posted By: rpn453


It is weird how hard it is to find GL-4 MTF compared to most other automotive fluids. I don't know of any synchronized manual transmissions where I would be inclined to use a GL-5, even if some say that it's acceptable. Which ones have you had success with using a GL-5?

Welcome to the forum!


I ran GL-5 in my 240sx race car. Granted, I was changing the stuff once a month

Also have run it in quite a few of the hot rods that we built. Borg-warner t-56's haven't had any problems either.

We ran it in our old rodeo (same vintage as my pathfinder) for over 200k miles, never had a problem. That's why I've never even known it was such a big deal. From what I read, it's only synchros made from soft brass that really care.

that said, I might as well just switch to GL-4 anyways. It's no more expensive, and even if 200k is fine, who knows what 300k might look like (and I expect transmissions to last that long)