I have a 01 2500 6-speed.

I'm about to start hauling a RV with it and need to change the factory fluids out of it.

The manual says to run 75w140 synthetic in rear diff. if towing. It says nothing of what to use if towing for the T/case or transmission.

What would you guys recommend??

Thank You!!!

 

I have had good luck with Amsoil universal ATF in the T case, and Amsoil syncromesh trans fluid in the transmission. I overfill my trans by removing the shift tower and dumping 6 quarts in from the top. If you remove the driver side PTO cover there is a magnet on the bottom of the trans case that should be cleaned. The 6 speeds are picky on using the correct type of fluid. Hope this helps

 

http://www.amsoil.com/shop/by-produc...n-fluid-5w-30/

 

Amsoil is great stuff if you want to spend the money.....

If not, I use Synthetics for the diffs/transfercase and the recommended fluid for the NV5600. I have Pennzoil synchromesh fluid in mine right now.

Also, for towing, I use the spicer sealed u-joints. The zerked ones are strong, but the solids are a lot stronger. Stockers should be solids.

Also, you may need to upgrade the clutch, depending on trailer weight and terrain...

 

Thank You all for the advice!

The RV is 4,500# empty. I only have 47,000 miles on my truck and just need to change out the fluids anyway. I will look closely at Amsoil in all the drivetrain.

I need to get a fuel pressure gauge put in it to before towing so I can keep my VP44 alive!!! I'm using Standrodine fuel addative with my fill ups, though I haven't yet run much low sulfer fuel thru it yet.

 

the nv5600 will last a lot longer if you use the following mix in a 50-50 ratio, fill the transmission and then add two more quarts. if you want to pay extra for amsoil sub the 5w-30 syncromesh for the syncromax.
Delo Synthetic Transmission Fluid SAE 50
Delo Synthetic Transmission Fluid SAE 50 delivers exceptional all-climate, year-round performance in heavy duty truck transmissions. A unique additive package can protect gears without using the “active sulfur” agents commonly found in automotive axle oils. This results in little to no corrosion and long life for copper-containing parts, such as oil coolers, bushings, and thrust washers. Good pumpability in extreme hot or cold temperatures promotes smooth shifting and efficient power transfer. It is specifically formulated to meet the latest extended drain requirements for Eaton transmissions, with drain intervals of up to 500,000 miles.
Synchromax is recommended for manual transmissions
that specify an automatic transmission fluid or motor oil.
It is also ideal for transfer cases and 2-cycle motorcycle
gear boxes.
Synchromax is formulated with Royal Purple’s synthetic,
proprietary Synerlec additive technology, offering
improved shift quality over a wide temperature range and
reduced gear noise.
Synchromax is fully compatible with all types of friction
materials and offers excellent corrosion and oxidation
protection without affecting the soft metals commonly
found in manual transmission synchronizers.
Performance Advantages
• Greater wear protection
• Smoother shifts
• Excellent rust / corrosion protection
• Reduces friction for more power
• Lowers operating temperatures

 

ummmmm, just curious old me here. You have a 12 year old truck and still have the factory fluids in it???????.

Regardless, in my 14 year old 1999 I change fluids pretty much on a regular basis because I tow a 12,000lb beauty queen. I tried synthetics' in the rear diff and had to drop them out and replace back to dino 80w90 weight. The clutch slippage in my LSD due to the synthetics was just brutal. On a left hand turn the rear wheels would jump off the pavement. YMMV

Cheers!

Mike

 

Thank You for the information

 

I use the Royal Purple SyncroMax in the trans & Royal Purple synthetic in the diff. No problems with either, and it shifts smooth.

 

You generally don't need to add limited slip additive to synthetic gear lube. The additive is to help the limited slip's clutches slip more, but good synthetic lube is usually already slippery enough.

Mike

 

I have Pennzoil Synchromesh in the NV5600, filled to 6 qts.

I have Valvoline Synpower in the diffs. No extra additive needed for the LSD clutches in the rear-end.

 

I have Royal Purple in the diffs and never have added any friction modifier in the rear. It will still hook both up in the dirt....

 

My understanding of FM additives was/is slightly askew. I now understand that I likely had too much slippage going on when I had synthetic oil + FM additive. I decided to go back to dino oil + FM because it worked without problems before and I change the diff fluid every year. I think that the other posted replies will give you ample alternatives to chose from if you decide to go with synthetic product.

Cheers!

Mike

 

Don fall victim to marketing manipulation. Because gear oil is not subject to a combustion process like engine oil, it will basically last forever as long as its not contaminated or overheated. There isnt anything the stuff on the shelf has that the stuff in your differential or tranny doesn't have in it.....unless there was a significant change in the recipe which would justify a need to change. The only reason you want to change on routine maintenance is to make sure there isnt water or debris inside or if you need to change viscosity weight. Need conformation?.....check the front differential lube on a part time 4wd (94-01) and you'll find nice honey colored oil in there.....unless water or condensation was allowed to enter somehow. Thats not me telling anyone not to pay attention and regularly check fluid conditions but to mindlessly change every 30k miles or so is simply throwing money away.

 

^^^Agree!