New Venture NV4500

NV4500 Transmission Ratios

*Reverse ratio changed from 5.61 to 5.04 : 1 beginning the 1998 model year

New Venture NV4500 Transmission Specs

NV4500 Manual Transmission Fluid Spec

The NV4500 features carbon fiber composite synchronizers and is therefore highly sensitive to transmission fluid type and viscosity. Failure to use an acceptable fluid may ultimately result in excessive synchronizer wear and/or failure. The original fluid spec is Castrol Syntorq synthetic 75W-90 GL-4. The fluid has become difficult, if not impossible to source (no longer produced by Castrol?). However, Chrysler and GM continue to offer their formulations, part numbers 12346190 (replaces 12346191) and 4874459 (replaces 4637579) respectively. The ACDelco oil is spec'd as a 75W-90, while the MOPAR fluid is spec'd as a 75W-85; both oils are the correct GL-4 lubricant developed for the NV4500. Amsoil 75W-90 manual transmission fluid is a popular alternative that also meets the NV4500's fluid specifications at a much lower cost. DO NOT confuse MOPAR's NV4500 compatible fluid with transmission fluid for the NV5600; the oil specs are entirely different. Avoid MOPAR 4874464; this is compatible with the NV5600 and NOT the NV4500. The OEM fluid is relatively expensive, however frequent transmission service is unnecessary and total long-term service costs are therefore relatively small.

An important component of the fluid spec is that it meets API GL-4 specifications, but this does NOT mean that any GL-4 gear oil of the same viscosity will suffice. This also does not infer that a GL-5 oil that meets GL-4 spec is compatible. Lubricants developed for synchronized manual transmissions such as the NV4500 must exhibit characteristics that include a balance between gear/bearing lubrication and synchronizer friction. Certain formulations may provide greater lubrication characteristics and reduce gearset wear, but at the expense at more rapid synchronizer erosion. A synchronizer requires a degree of friction in order to increase or decrease the angular velocity of a gearset and allow for smooth gear progressions. In addition, the NV4500's carbon fiber synchronizers may deteriorate if an incorrect fluid is used. NV4500 owners are therefore ill advised to stray from the factory intended fluid spec and should err on the side of caution by selecting an OEM transmission fluid or confirmed suitable alternative.

NV4500 Loss of 5th Gear

Though the strength and reliability of the NV4500 is relatively high, it does have a fatal flaw - the 5th gear lock nut has a tendency to back off, making the transmission inoperable in 5th gear. The problem is limited to Dodge Cummins applications, and GMC/Chevrolet trucks equipped with the NV4500 do not typically experience the problem. When this occurs, it becomes physically impossible for a driver to place the transmission in overdrive. The problem is fairly common and often caused by frequently lugging the engine in 5th gear. As a result, owners are advised to avoid high load (towing), low speed operation in 5th gear. Although the Cummins engine makes excellent low end torque and exhibits the performance characteristics necessary to lug the engine down low, it adversely affects transmission reliability.