2018 Ram 3500 Transmission Fluid & Service

Quick Answer

• Transmission Make/Model: Aisin AS69RC
• OEM Fluid Spec: Mopar AS69RC ATF (SAE 0W-20, MS-9602 compliant)
• Drain & Fill Capacity: Approximately 7-8 quarts
• Full Overhaul Capacity: Approximately 17.5 quarts
• Filter OEM Part Number: Verify with dealer or service manual (typically a pan-mounted filter and an inline filter)
• Recommended Service Interval: 30,000 miles for severe duty/towing, 60,000 miles for normal duty

Fluid Type Explained

The 2018 Ram 3500 with the 6.7L Cummins diesel engine primarily utilizes the Aisin AS69RC automatic transmission. This heavy-duty transmission requires a specific fluid to ensure its longevity and proper operation. The OEM fluid spec is Mopar AS69RC ATF, which is a specialized SAE 0W-20 fluid meeting Chrysler's MS-9602 specification. It is crucial to use only this specified fluid or an aftermarket equivalent that explicitly states compliance with MS-9602.

Using an incorrect fluid can lead to a variety of issues, including: decreased lubrication, excessive heat generation, premature wear of internal components (clutches, seals, bearings), erratic shifting, and ultimately, transmission failure. The AS69RC transmission, being a sophisticated unit designed for heavy loads and towing, relies heavily on the correct fluid properties for optimal performance and protection.

Service Procedure

Servicing the Aisin AS69RC transmission typically involves either a drain and fill or a fluid exchange. For the average owner, a drain and fill is the more accessible option, though it only replaces a portion of the total fluid.

Drain & Fill: This procedure involves draining the fluid from the transmission pan, replacing the pan-mounted filter (if applicable), and refilling with new fluid to the correct level. This method typically replaces around 7-8 quarts of fluid. While simpler, it leaves a significant amount of old fluid in the torque converter and cooler lines, which will mix with the new fluid. Regular drain and fills are beneficial for maintaining fluid quality over time.

Full Fluid Exchange (Flush): A full fluid exchange involves using a specialized machine to circulate new fluid through the entire transmission system, including the torque converter and cooler. This process removes nearly all of the old fluid and replaces it with new, clean fluid. This procedure is more comprehensive and often recommended for vehicles with higher mileage or when a significant period has passed between services. Some manufacturers advise against traditional pressure flushing, so it's always best to consult your service manual or a qualified technician regarding the recommended fluid exchange method.

Regardless of the method, always ensure the transmission is at the correct operating temperature and check the fluid level according to the manufacturer's instructions. Overfilling or underfilling can both lead to transmission problems.

Service Interval

The service interval for your 2018 Ram 3500's AS69RC transmission depends heavily on usage.

• Normal Duty: For vehicles primarily used for light hauling and daily driving without heavy towing, a service interval of 60,000 miles is generally recommended.
• Severe Duty / Towing: If your Ram 3500 is frequently used for heavy towing, hauling heavy loads, off-roading, or in extreme temperatures, a more aggressive service interval of 30,000 miles is highly advisable. These conditions place significant stress on the transmission and its fluid, leading to quicker degradation.

Ignoring recommended service intervals can lead to premature wear, reduced fuel economy, and potential transmission failure, which can be a very costly repair.

Common Transmission Problems

While the Aisin AS69RC is a robust transmission, like any mechanical component, it can experience certain issues, especially if maintenance is neglected. For the generation of the 2018 Ram 3500, some common potential problems or points of concern include:

• Fluid Degradation: As mentioned, neglecting fluid changes in severe duty can lead to fluid breakdown, reducing its lubricating and cooling properties. This can manifest as harsh shifts, slipping, or overheating.
• Solenoid Issues: The AS69RC relies on a series of solenoids to control fluid flow and shifting. Failing solenoids can cause delayed shifts, erratic shifting, or even a "limp mode" where the transmission locks into a single gear to prevent damage.
• Torque Converter Problems: Issues with the torque converter can lead to shuddering, slipping, or a feeling of the engine revving without a corresponding increase in speed. This can sometimes be related to fluid quality or internal wear.
• Valve Body Concerns: The valve body is the control center of the transmission, directing fluid pressure to activate clutches. Problems here can cause a variety of shifting complaints. While less common on properly maintained units, it's a complex component to diagnose.
• Cooling System Issues: Overheating is a primary enemy of automatic transmissions. Ensure your transmission cooler and lines are free of debris and functioning correctly, especially if you tow heavily.

Regular maintenance, using the correct fluid, and monitoring for any unusual shifting behavior or noises are the best ways to prevent serious transmission problems.

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