19/10/2005
Maintaining Your Cub RZT50: A Comprehensive Guide to Transmission Fluid
The Cub RZT50 is a robust zero-turn mower designed for tackling demanding garden and lawn care tasks. Like any sophisticated piece of machinery, regular maintenance is key to ensuring its longevity and optimal performance. One of the most crucial, yet often overlooked, maintenance aspects is the transmission fluid. This guide will walk you through everything you need to know about the transmission fluid for your Cub RZT50, including capacity, the recommended oil type, and a detailed procedure for changing it.
Understanding Your Cub RZT50's Transmission
Your Cub RZT50 is equipped with two Hydro-Gear EZT integrated transaxles. These are the heart of your mower's drive system, allowing for smooth and precise manoeuvrability, especially the characteristic zero-turn capability. The proper functioning of these transaxles relies heavily on the quality and level of the transmission fluid. This fluid not only lubricates the internal components but also helps to dissipate heat generated during operation, preventing overheating and premature wear.
How Much Oil Does a Cub RZT50 Use?
Each Hydro-Gear EZT transaxle in your Cub RZT50 has a specific oil capacity. While the exact amount can vary slightly, each unit typically holds approximately 52.4 ounces of oil. This translates to a little over a quart and a half per transaxle. Therefore, for a complete fluid change on both transaxles, you will need approximately 105 ounces of oil, or just under three quarts in total. It's always wise to have a little extra on hand for topping up or in case of minor spills during the process.
What Type of Oil is Recommended?
Hydro-Gear, the manufacturer of the EZT transaxles, specifically recommends using 20W-50 engine oil for refilling these units. This viscosity is chosen for its ability to provide adequate lubrication and protection across a range of operating temperatures that these mowers typically encounter. Using the correct type of oil is paramount. Using an oil with an incorrect viscosity could lead to insufficient lubrication, increased wear, and potential damage to the transaxle's internal components. Always ensure you are using a quality 20W-50 engine oil that meets the appropriate specifications, often found in your Cub Cadet owner's manual.
The Transmission Fluid Change Process: A Step-by-Step Breakdown
Changing the transmission fluid on a Cub RZT50, particularly the Hydro-Gear EZT transaxles, can be a bit of a fiddly job. Unlike simpler transmissions, these units do not have a convenient drain plug at the bottom. The recommended method for draining and refilling involves removing the transaxle, inverting it, and draining the fluid through the top vent. While this might sound daunting, with the right approach and a bit of patience, it's a manageable task for the home mechanic.
1. Preparation and Safety First
Before you begin, ensure your mower is on a level surface and the engine is cool. Safety is paramount. Wear appropriate personal protective equipment, including gloves and eye protection. You'll need a few tools and supplies:
- 20W-50 engine oil
- A siphon pump (easily available from auto parts stores or online)
- A small diameter hose that fits the siphon pump
- A funnel with a narrow spout or tubing attachment
- A 1/4 inch Allen wrench or socket
- A breaker bar or pipe for leverage (if needed)
- A clean container for used oil
- Cleaning supplies (rags, compressed air, degreaser)
2. Cleaning the Work Area
Thorough cleaning is essential to prevent dirt and debris from entering the transmission during the fluid change. Use a high-pressure water stream or compressed air to clean the areas around the transaxles, focusing on the top of the transmission and the engine deck where the vent port is located. Once clean, wipe down the area with a clean rag to remove any remaining residue.
3. Locating and Removing the Fill Plug
The fill/vent port is typically located on the top of the transaxle, often with a plastic vent tube attached. Carefully remove this vent tube, being mindful not to damage the plastic barb it connects to. Next, using your 1/4 inch Allen wrench or socket, loosen and remove the fill plug. If the plug is tight, a breaker bar or a pipe slipped over the wrench can provide the necessary leverage. Remember, the goal is to break it loose, not to strip the head.
4. Draining the Old Fluid
With the fill plug removed, you'll need to siphon out the old transmission fluid. Insert the hose of your siphon pump into the fill port. You may need to move the hose around to ensure you're drawing fluid from the lowest possible point within the transaxle. Siphon out as much of the old, dirty fluid as possible into your designated container. This process can be slow, as the fluid is quite thick. Be patient and continue pumping until no more fluid can be drawn out. Some sources suggest that to effectively drain the entire volume, the transaxle may need to be removed and inverted, but for a routine fluid change, siphoning through the top vent is a common approach.
5. Refilling with New Fluid
Once you've removed the old fluid, it's time to add the fresh 20W-50 engine oil. Attach a length of tubing to your funnel's spout to help guide the oil down through the fill port and engine deck opening. Slowly pour in the new oil. Start by adding approximately 24 ounces per transaxle, which is slightly less than the total capacity. This allows you to check the level accurately after the initial run. Many mechanics recommend filling the transaxle until the fluid level is about one inch from the top of the fill port.
6. Replacing the Plug and Purging the System
After refilling, reattach the vent tube securely to its barb. Then, replace the fill plug and tighten it appropriately. Now comes the crucial step of purging any air pockets from the hydrostatic transmission. To do this, with the transaxles filled and the fill plug replaced, start the mower's engine. Engage the parking brake, disengage the transmission (ensure the mower is not in gear), and slowly move the control levers forward and backward several times. Allow the engine to run at a normal operating speed during this process. This circulation helps to push out any trapped air and ensures the fluid is distributed throughout the system. After purging, you can check the fluid level again and top up if necessary, ensuring it remains at the recommended level.
Important Considerations and Tips
Hy-Tran Filter: The provided information does not specifically detail the removal of a 'Hy-Tran filter' for Cub Cadet models generally, or specifically for the RZT50. The process described focuses on the transmission fluid change itself. If your RZT50 has a separate filter that requires replacement, consult your owner's manual or specific service documentation for that procedure. However, the EZT transaxles themselves do not typically have easily accessible external filters that are part of a routine fluid change.
Fluid Level Check: After the initial fluid change and purging, it's a good practice to check the fluid level again after your first mowing session. As the system settles and the fluid circulates, the level might drop slightly. Top up as needed to maintain the correct level.
Fluid Disposal: Always dispose of used motor oil responsibly. Take it to a local recycling centre or an auto parts store that accepts used oil.
Frequently Asked Questions
Q1: Can I use a different type of oil in my Cub RZT50 transmission?
It is strongly recommended to use only the manufacturer-specified 20W-50 engine oil. Using a different viscosity or type of oil can lead to damage.
Q2: How often should I change the transmission fluid?
Consult your Cub Cadet owner's manual for the recommended service intervals. Generally, transmission fluid changes are recommended every few hundred hours of operation or every few years, whichever comes first.
Q3: Is it necessary to remove the transaxles to change the fluid?
While inverting the transaxles offers the most thorough draining, siphoning through the top fill port is a common and often sufficient method for routine maintenance. If you suspect significant internal contamination, a more thorough flush or professional service might be considered.
Q4: What are the symptoms of low or old transmission fluid?
Symptoms can include reduced mower performance, hesitation when changing direction, overheating, and unusual noises from the transaxles.
By following this guide, you can effectively maintain the transmission fluid in your Cub RZT50, ensuring it continues to provide reliable service for years to come. Remember, regular maintenance is the best way to prevent costly repairs and keep your lawn looking its best.
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