So I just bought this truck and have been doing all the standard tune up and fluid changes. I have been doing some research on these 4500 HD Manual transmissions and apparently there is a lot of discussion on what kind of fluid you should use. Some say Royal purple is excellent and other say that they have had a lot of trouble once they started using royal purple. The two that were recommended were:

Mopar Manual Transmission Lubricant (PN 4637579)
75W-90 Castrol Syntorque Synthetic

Does anyone have any input on this?

 

Let me clarify. My build sheet says my truck has:

DBBC All Manual Transmissions
DDC 5-Speed HD Manual Transmission

So I am unsure about what exact transmission model I have.

 

These are the three I see 'suggested'.

+ 75W-90 Castrol Syntorque Synthetic
+ Mopar Manual Transmission Lubricant (PN 4637579)
+ GM Transmission oil (PN 12346191)

See which is least expensive. Go with that.

 

Since you have a 318, the trans will be the NV3500. I used the fluid from chrysler and it hasn't been a problem.
Gord.

 

Awesome. I wish they would have made this easier to find! I even called Chrysler and got "Our records only go back to '03 sir, Sorry."

Very Good Gord! I appreciate the info. I will get some of that oil this weekend!

 

Ya, they should have listed it on the build sheet. One place i know it's listed is the tag on the underside of the hood (if yours still exists/is readable).
Gord.

 

My NV3500 was shifin a little rough and seeming like it was getting stuck in 5th when you came of the freeway. I change out what was in there for AmsOil syncromesh stuff. It's been in the "flushing phase" for about 400 miles. Soon as I get a chance I'll dump and refill. Even though my syncros may be going bad the thing shifts like night and day now. There are still some issues, but it shifts much better than it did. The AMSOil will run you about $10.xx a quart, will use almost 2 quarts.

p.s. you will need 2 different sized allen wrenches. Found the big one at Ace and the smaller one at Sears...ack! 17mm and 7/16????? Don't remember off the top of my head.

 

Excellent information here guys. One more question though, I called the dealership and they told me they put in mopar 75W-85 Part #4874459 VERY PRICEY at $23 a quart. Thats obviously not what the manual and such calls for. The dealership also said other off brands were fine as there are no special additives or anything fancy about the oil. So what brand does every use and like?

 

After looking at the gear lubricants tests I am almost sold on amsoil severe gear 75W-90

 

They're wrong, the fluid for the NV3500 is no where near a 75W-85 weight. I believe the NV4500 takes that weight of fluid though. Also, on the bottle of mopar fluid, it says specially formulated for the NV3500 or something similar.
Gord.