My 89 Dakota LE service manual says to use 10-30 oil in the 5 speed MANUAL transmission. SO.. will a full synthetic be ok? I don't see why not but thought I'd get some feedback before changing.

thanks......

ps its a NP2500 tranny.

 

No. What youre looking for is oil with syncromesh. Its the same viscosity as motor oil, but its not actual motor oil.

 

Is that true? What tranny did the 89 have? The AX-5? AX-15? I don't remember. In any case I'm nearly positive that the new spec for the AX-15 is motor oil, straight motor oil. I used Redline gear oil anyway because it gets great reviews for the winter. And really it does work fantastic. But the Jeep guys who do 10w30 all report great performance too.

I thought the reason they went to motor oil is because people were putting some gl5 fluids in that ate at the brass synchros...people like me. Once I learned that gl5 was risky I quickly drained it.

 

Quote:

Originally Posted by Toby Warford

No. What youre looking for is oil with syncromesh. Its the same viscosity as motor oil, but its not actual motor oil.

On my 87 with a nv2500 transmission, the manual says 10w30 motor oil. (not syncromesh) I used mobil 1 in it. But when I switched to the NV3500 trans, it calls for 10w30 syncromesh......

But I believe the 10w30 synthetic motor oil is fine for your 89

 

I know this is an old thread but I'm struggling with this exact issue. I can't find any consistent info on what to use. Autozone said 75w-90 I think. It's a 1995 2.5 manual.

 

Back in the 1980's car companies started using lighter oils in transmissions. I had an '88 S-10 with a 5 speed and it required automatic transmission fluid. I'd go with what your owners manual says to use. As for 75W-90, that's gear lube for the rear end.

 

So it's the AX-15 .

Here's a write up on the suggested replacement from Allpar:

https://www.allpar.com/fix/gear-oil.html

So 75W90 or the Mobil 1 they say is the equivelent for the non-NV3500s.

RwP

 

hey, if I understand correctly (bear with me I'm kinda slow) is to use the Mobil 1 75w-90. I'm just trying to make sure I ask for the right thing at the parts store

 

For a AX-15, I'd ask for the Pennzoil SyncroMesh.

It's a replacement for the Mopar liquid.

If you get the Mobil 1, make sure it's GL-4 not GL-5; GL-5 eats the syncros.

RwP

 

Thanks for the info. just to confirm, in the 4 cylinder manual Dakotas, AX-15 was the only option? sorry for all the questions. I come from an air cooled background and I inherited this truck from my father in law.

EDIT: when i decoded the vin the trans came back as DDQ