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Maintaining Your Argo’s Kohler Aegis Engine

If you own an Argo Avenger or a Conquest, it’s probably powered by a Kohler Aegis V-Twin. This liquid-cooled, fuel-injected engine is renowned for its reliability, and it’s easy to maintain. Here’s what you need to know to keep it running.

Maintenance Schedule

Your Argo’s gauge cluster has a built-in hour meter to keep track of maintenance.

Every 200 hours: Change oil and oil filter. Replace the main fuel filter.
Every 250 hours: Replace the outer air cleaner element. Check the inner element.
Every 500 hours: Replace the inner air cleaner element and spark plugs.
Every 1,000 hours: Change the engine coolant.
Every 1,500 hours: Replace the EFI fuel filter

Kohler recommends having a professional mechanic replace the fuel filters.


Kohler recommends SAE SJ class or higher motor oil. The viscosity you need depends on your operating conditions.

10W-30: 0°F and higher
SAE 30: 50°F and higher
5W-30: 32°F and lower

The engine holds 1.7-1.9 quarts.

When checking the oil, be sure to push the dipstick all the way into the dipstick tube.

Since the engine is mounted inside the hull, Argo recommends using a pump to draw the oil out of the dipstick tube instead of using the drain plug. If you do remove the plug, torque it to 20 ft-lbs. when reinstalling.

When installing a new oil filter, fill it with fresh oil and let it sit for a couple of minutes to let the filter media absorb the oil. Apply a thin layer of clean oil to the rubber seal.

Air Filter

Replace the paper element when it’s dirty. Do not clean it with compressed air.

To change the air filter:

1. Unhook the two latches on the end cap. Slide the cap off of the filter.
2. Clean the inlet screen and dust ejector valve on the end of the cap.
3. Pull the air cleaner elements out of the housing. Separate the inner and outer elements and inspect them. Replace visibly dirty filter elements.
4. Inspect the housing, cap, and filters for signs of cracks and damage. Replace as needed.
5. Reassemble the air filter with the dust ejector valve facing down. Make sure both ends of the breather tube are connected.


While EFI engines are more tolerant of stale fuel than carbureted engines, Kohler still recommends using fuel within 30 days of purchase. For long term storage, add a fuel stabilizer and run the engine for two to three minutes to draw the treated fuel through the fuel system.

Spark Plugs

The electrode gap for both spark plugs is 0.03 inches (0.76 mm). When installing the plugs, torque them to 20 ft-lbs.

Cooling System

The radiator has a small screen that protects it from bugs and debris. This screen should be cleaned periodically. The fluid level in the coolant reservoir, mounted behind the radiator, needs to be kept between the “Add” and “Full” marks. Kohler recommends a 50/50 mix of ethylene glycol-based antifreeze and water. Concentrations up to 70% can be used when operating at temperatures over 108°F.

To change the coolant:

1. Let the engine cool completely to reduce coolant system pressure.
2. Slowly loosen the radiator cap to bleed off any remaining pressure.
3. Set a container under the radiator. Unscrew the drain plug.
4. Once the radiator is empty, remove the overflow hose from the reservoir. Unhook and slide the reservoir off of its mount, then pour the contents into the drain pan.
5. Reassemble the cooling system. Apply Teflon thread tape to the drain plug to ensure a tight seal.

Next, flush the cooling system:

6. Fill both the radiator and fluid reservoir with water and cooling system cleaner approved for aluminum engines.
7. Run the engine until it reaches operating temperature, then shut it off. Wait for it to cool.
8. Follow steps 1-5 to drain the cooling system.

Finally, fill the cooling system:

9. Do a quick check of the hoses and clamps that transfer fluid between the radiator, coolant reservoir and engine. Replace as needed.
10. Add coolant to the radiator and reservoir. The system holds about 2.1 quarts. Be patient when adding fluid to the radiator. It takes a while for the coolant to flow through the pipes.
11. Run the engine for 5 minutes, then shut it off and let it cool down.
12. Check the coolant reservoir and add more coolant as needed.

Get Everything You Need for Your XTV at Shank’s Argo

Are you ready to explore the outdoors in your own Argo XTV? Is your amphibious ATV’s engine due for a tuneup? Then you should visit the experts at Shank’s Argo. We can help you find the right XTV for your needs, and we offer the parts and service support you need to keep it running. Visit our shop at 4900 Molly Pitcher Highway in Chambersburg, PA.

You can also schedule a demonstration at our website,

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