89 Dakota Manual trans fluid change.

[kafka45]

Ok.. its time to do a Manual transmission,(an NP2500), fluid change on this beast
The 89 Service manual says to use 10-30 oil. I feel stupid asking, but is this the
way to go 28yrs later? takes 2 qts. and I'm assuming a full synthetic is ok..

appreciate the feedback..

k

 

[RooflessVW]

10W-30 would of course be fine, whether you choose conventional or synthetic. You could also run an MTF or a GL4 75W-90.

 

[OneEyeJack]

I ran Mobil 1 10w-30 in my 84 Civic wagon 5-speed. It was spec'd for 10w-30 dyno oil and I thought this synthetic oil would be better. I found out that although engine oil is the correct viscosity it shears down too much. I rebuilt the transmission at 200K because of bearing noise. I replaced the bearings, seals, and gaskets but no gears or other hard parts. The UOA showed that the oil had sheared down quite a bit.

This time I used Red Line MTL and at 440,000 miles there's no noise, shifts great and this new oil has not sheered down. It costs a bit more but since I only change it every 60K it's worth it to me. The Mobil 1 I'd previously use was changed every 30K and still had the shearing problem.

 

[zeng]

1980's ..... pick any 80W90 GL4.

 

[mattwithcats]

I had a 1988 Dakota...

Full synthetic caused leaks,

10W-30 full Dino was really hard to shift in the cold...

I used Shell Rotella T5 semi synthetic in 10W-30...

 

[Bottom_Feeder]

The last time I used a full synthetic (Mobil 1) in a manual transmission that called for regular motor oil (a '94 del Sol) it HATED it. Nothing but grinds and missed shifts. Went back to a name-brand dino oil in short order and it was mostly fine after that but never 100%. One of the many 'one step forward, two steps back' issues I had with that poor car. It deserved better.

Personally, I wouldn't use a full synthetic fluid in a transmission unless it was designed specifically for that purpose.

 

[SwampSurvivor]

I have a transmission that is also recommended 10w-30 per revised service information. 10w-30 is still the way to go in it.

I did end up putting in 15w-40 because it's cheaper and it's a beater.

 

[JamesBond]

I would use Pennzoil synchromesh, it is slightly thinner than 10w30 at operating temperature but is designed for transmissions. I don't think newer motor oils have the same additives that they did when your owners manual was written. I've used synchromesh in several different vehicles that call for thicker or thinner fluid and it has always worked well.

 

[4WD]

Redline MTL gets used in synchromesh applications - have it in my transfer case.
Notice the nectar color:

 

[MolaKule]

Originally Posted By: mattwithcats
I had a 1988 Dakota...

Full synthetic caused leaks,

10W-30 full Dino was really hard to shift in the cold...

I used Shell Rotella T5 semi synthetic in 10W-30...



If you had a degraded and false seal before using synthetic, sure it will leak.


My two picks would be Amsoil MTF (Manual Synchromesh Transmission Fluid, 75W80 GL-4, 5W-30)

and

Redline MTL 75W80 GL-4 Gear Oil.