Looking at changing the transmission fluid in both vehicles. The 5spd has 18k miles (5th wheel hauler) and the 6spd has 13K - mainly highway miles.<br><br>The Haynes service (2001) manual doesn't have the NV5600--anyone know the quantity?<br><br>The manual says to remove the pto cover to drain the fluid. Looks like there is black sealant seaping through the cover/housing - the manual doesn't specify what it is...anyone know?<br><br>

 

I wouldn't change them, there have hardly any miles. If you do want to do something open top via the floor board/shifter area and add 2 bottles of Lucas to each.<br><br>Unless the fluid is really dirty I would change it. <br>Capacity of the 5600 is 4.5 liters.<br><br>If you do change it be sure to use exactly what is labeled on on the transmission or else the rear seal will go bad and dump all the fluid into the transfercase if 4X4. I believe they are different for 4500 and 5600.<br><br>I have 130k on my tranny fluid -still looks great. I check from the top since it is overfilled.

 

The correct fluid for the NV4500 is Castrol Syntorq LT 75W-85, which is a synthetic gear lube. Capacity is 4 quarts. I don't know what the NV5600 takes. Be prepared to shell out $$$ for the Syntorq.<br><br>I changed mine at 60K miles and used big A series 2000 75W-90. I used the red RTV high temp silicone for new gaskets on the PTO cover. Some I've noticed install fast coolers on their transmissions in place of PTO covers, helps keep 'em cool and adds fluid capacity. Pricey, but if towing alot, probably worth it.

 

Per my 2000 Service Manual the NV5600 takes approx. 9.5 pints dry fill. Unless your bored I would not change the fluid in the NV5600 until you have 40-50K miles on it. JMHO<br><br>PS per the service manual, after you drain the fluid from the bottom bolt hole of either of the PTO covers you need to apply sealer to the bolt thread before installing it during a lubricant change. Correct fill level is to the bottom of the fill plug hole and make sure it is level when you service it. Also &quot;ONLY&quot; use Mopar manual transmission lubricant P/N 4874464. This is the only lubricant recommended for use, warranty will be void if you have a failure with any other lubricant.

 

I changed the fluid on my 4500 at 126,000 when I changed the clutch. Made me wonder why I spent the 80 bucks. Looked new and clean. At 165,000 all towing heavy the od is still working well and quiet.