2020 Ram 3500 Transmission Fluid & Service Guide

As an ASE-certified master technician, I know that the transmission is the heart of your truck's capability. For a heavy-duty workhorse like the 2020 Ram 3500, understanding and maintaining your specific transmission is crucial for longevity and performance. Ram offered three different automatic transmissions in the 2020 3500-series, each with unique fluid and service requirements. Getting this wrong can lead to premature wear, poor performance, and costly repairs.

This guide will walk you through the correct fluid types, capacities, filters, and service schedules for your truck, whether it's equipped with the 6.4L HEMI or the 6.7L Cummins engine.

Quick Answer

Here are the essential specifications for the transmissions found in the 2020 Ram 3500.

For Ram 3500 with 6.4L HEMI V8:

• Transmission Model: ZF 8HP75-LCV 8-Speed Automatic
• OEM Fluid Spec: Mopar ZF 8&9 Speed ATF (P/N 68218925AB) or an equivalent licensed fluid.
• Drain & Fill Capacity: Approximately 5.5 quarts
• Full Overhaul Capacity: Approximately 9.0 quarts
• Filter OEM Part Number: The filter is an integral part of the transmission pan. The entire pan assembly must be replaced. Verify the correct part number with your dealer or service manual.
• Recommended Service Interval: Check fluid at 100,000 miles under normal conditions. For severe duty (towing, hauling, frequent stop-and-go), a 60,000-mile interval is recommended.

For Ram 3500 with 6.7L Cummins (Standard Output):

• Transmission Model: Chrysler 68RFE 6-Speed Automatic
• OEM Fluid Spec: Mopar ATF+4 (P/N 68218057AC)
• Drain & Fill Capacity: Approximately 6.5 quarts
• Full Overhaul Capacity: Approximately 12.5 quarts
• Filter OEM Part Numbers: This transmission uses two filters. It is critical to change both. Verify part numbers with your dealer.
  • Sump Filter (in pan): Mopar P/N 5013470AC
  • Spin-on Cooler Line Filter: Mopar P/N 68109834AA
• Recommended Service Interval: 60,000 miles for filter and fluid change, regardless of normal or severe duty use.

For Ram 3500 with 6.7L Cummins (High Output):

• Transmission Model: Aisin AS69RC 6-Speed Automatic
• OEM Fluid Spec: Mopar Aisin Transmission Fluid (ASRC / AW-2) (P/N 68186575AB). Do NOT use ATF+4 in this transmission.
• Drain & Fill Capacity: Approximately 7.5 quarts
• Full Overhaul Capacity: Approximately 15.5 quarts
• Filter OEM Part Number: A single sump filter is used. Verify the correct part number with your dealer or service manual.
• Recommended Service Interval: 30,000 miles for severe duty or 60,000 miles for normal duty.

Fluid Type Explained

Using the correct transmission fluid is non-negotiable. Each fluid formulation has a specific friction coefficient, viscosity, and additive package designed for the materials and hydraulic pressures in its corresponding transmission.

• ZF 8&9 Speed ATF: This is a high-performance synthetic fluid designed for the specific clutch materials and rapid hydraulic actuation inside the complex 8-speed ZF transmission. Using anything else will cause shifting problems and internal damage.
• Mopar ATF+4: This is the long-standing fluid for most Chrysler-built transmissions like the 68RFE. It offers excellent shear stability and thermal resistance. It is critical for proper torque converter clutch engagement. It is NOT compatible with the Aisin or ZF units.
• Aisin ASRC (AW-2): The Aisin is a commercial-grade transmission built by a Toyota subsidiary, and it demands its own specific fluid. This fluid is designed for high-heat, high-torque applications. Using ATF+4 or any other fluid will lead to rapid clutch wear and valve body failure.

Service Procedure: Drain & Fill vs. Full Exchange

A standard drain and fill service, where the pan is dropped and the fluid drains out via gravity, only replaces about 50-60% of the total fluid. The rest remains trapped in the torque converter, valve body, and cooler lines. While better than no service, it leaves a significant amount of old, degraded fluid in the system.

A full fluid exchange, performed with a professional machine, connects to the cooler lines and uses the transmission's own pump to swap nearly 100% of the old fluid with new fluid. For heavy-duty trucks, this is the superior service method as it ensures the entire system is protected by fresh fluid.

• For the 68RFE and Aisin: A drain and fill is a common DIY task, but a full exchange is recommended.
• For the ZF 8HP75: Servicing this transmission requires replacing the entire pan/filter assembly. The fill procedure is also more complex, requiring monitoring of transmission temperature to ensure the correct level is achieved.

Service Interval: Normal vs. Severe Duty

What qualifies as "severe duty"? For a Ram 3500, almost any work you do with it falls into this category:

• Towing trailers or hauling heavy loads (especially over 5,000 lbs)
• Frequent stop-and-go driving in hot weather
• Driving in dusty or mountainous environments
• Commercial use (plowing, delivery)

Unless you drive your Ram 3500 empty on the highway exclusively, you should follow the severe duty maintenance schedule. Transmission fluid is a wear item; it breaks down with heat and cycles. For a truck designed to work hard, preemptive fluid changes are the cheapest insurance against a transmission rebuild.

Common Transmission Problems

Even with proper maintenance, each transmission has its own characteristics and potential failure points.

• ZF 8HP75: Generally a very robust and reliable unit. Most issues are electronic, with some owners reporting occasional harsh shifts that can sometimes be corrected with a software update from the dealer.
• 68RFE: This is the weak link in the Cummins powertrain. It is known for struggling with the Cummins' torque, especially if power levels are increased. Common failures include failed torque converters, burnt-out overdrive clutches, and valve body cross-leaks leading to slipping and shifting issues.
• Aisin AS69RC: Significantly more durable than the 68RFE and well-suited to the High Output Cummins. It's a true medium-duty commercial transmission. Some drivers may notice firmer or "bus-like" shifts, which is normal. Keeping up with the 30,000-mile severe service interval is critical to its long life, as debris can cause issues with the sensitive valve body and solenoids.

Find a trusted shop on Repairius.