MikeyB

Have to say Amsoil MTF finally gave up the ghost in the NV5600 after 8 years and 50k miles of service. Late last week I noticed difficulty in shifting and on Friday barely was able to get into gear either stopped or rolling. Once it warmed up it started shifting fine again. Thinking it was either the fluid or the clutch hydraulics I decided to swap the fluid out first. In a hurry I grabbed 7qts of Pennzoil Synchromesh Fluid and swapped out the old fluid. Immediately the transmission went back to its normal shifting routine.

That was an easy fix.

Probably will swap out the hydraulics in the next few month as a PM.

carl48

dump two or three more quarts in it through the shifter.

MikeyB

The recommendation is 9 quarts now for the NV5600?

If so I might dump in couple of quarts of MT-90 or 50w transmission fluid.

carl48

use the 50 wt, here is the best two to use. ww granger has the delvac equal to the delo and o'rileys carries the Castrol syngear cd50 equivalent. the royal purple syncromax from napa or most anywhere. 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

carl48

forgot to add, blend the two in a 50-50 mix

MikeyB

Thanks.

Wonder if the Lucas Synthetic 50w Transmission Fluid is good? O'Reilly's sells it by the gallon jug.

carl48

it says it is equal to the delo same eaton spec