There has been much controversy regarding lubricant selection for the G56, with many owners and industry experts arguing that using ATF+4 to lubricate the transmission, as Chrysler recommends, can cause it to fail prematurely. Mercedes-Benz recommends a thicker 75W or 90W gear oil in their trucks that are equipped with the G56. It is debatable whether anything is gained by switching to a 75W/90W gear oil, but many owners choose to do so. A tooth was removed from the input shaft gear for the 2007.5 model year, resulting in a ratio change for the 6.7L Cummins version. When equipped in 6.7L Cummins applications, engine torque was derated to 610 lb-ft for 2007.5 to 2012 model years and 660 lb-ft for 2013 to 2018 model years. Thus, 6.7L Cummins owners who opted for the manual transmission option surrendered a significant amount of engine performance.
G56 Transmission Ratios
Application |
1st |
2nd |
3rd |
4th |
5th |
6th |
R |
2005 - 2007 Ram 2500/3500 |
6.29 : 1 |
3.48 : 1 |
2.10 : 1 |
1.38 : 1 |
1.00 : 1 |
0.79 : 1 |
6.29 : 1 |
2007.5 - 2018 Ram 2500/3500 |
5.94 : 1 |
3.28 : 1 |
1.98 : 1 |
1.31 : 1 |
1.00 : 1 |
0.74 : 1 |
5.42 : 1 |
G56 Transmission Specs
Transmission: |
Mercedes-Benz G56 |
Type: |
6 speed manual transmission |
Manufacturer: |
Mercedes-Benz |
Predecessor: |
New Venture NV5600 |
Model Years/Applications: |
2005 - 2010 Dodge Ram 2500/3500 (5.9L/6.7L Cummins turbodiesel) |
Synchronized: |
Synchronized in all forward gears and reverse |
Case Material: |
Aluminum |
Max Input Torque: |
N/A, suggested under 700 lb-ft |
Weight: |
~ 200 to 225 lbs |
Fluid Capacity: |
~ 4.95 quarts (9.9 pints) |
Fluid Type/Spec: |
MOPAR ATF+4 automatic transmission fluid (recommended by Ram Trucks) |
Service Intervals: |
Replace transmission fluid every 60,000 miles |
Features: |
• Designed specifically for light and medium duty diesel truck applications |
Both the NV5600 and G56 manual transmissions were available
during the 2005 model year - transmissions can be identified by their shift pattern