Service the Automatic Transmission

The Dodge Charger LX (2006–2010) is equipped with the NAG1 (W5A580) 5-speed automatic transmission. Unlike older Chrysler gearboxes, it is a sealed unit with no dipstick, which means fluid checks and servicing follow a specific procedure. This guide explains the fluid type, service interval, and how a DIY owner can handle drain and refill maintenance.

Transmission Fluid Type

• Always use Mopar ATF+4 or an approved equivalent.
• Do not mix with other ATF types — incorrect fluid can cause shifting issues and long-term damage.

Service Interval

• Normal driving: fluid is “filled for life” — no regular dipstick checks are needed.
• Severe duty (towing, stop-and-go traffic, hot climates): change fluid and filter every 60,000 miles (100,000 km).
• If shifting becomes harsh or delayed, a fluid/filter change may help.

Tools & Supplies

• Socket set and Torx bits (for transmission pan bolts)
• Torque wrench
• Drain pan (at least 8 L)
• Funnel and long hose for refill
• Transmission filter kit with pan gasket
• 4–5 L of Mopar ATF+4 (for drain/refill)
• Infrared thermometer or scan tool (to check fluid temperature)

Step 1: Draining the Fluid

1. Raise the car securely on axle stands.
2. Place a drain pan under the transmission pan.
3. Loosen the pan bolts gradually — fluid will begin to drain as the pan lowers.
4. Remove the pan completely and pour out the old fluid.

Step 2: Replacing the Filter

1. Remove the old transmission filter (held with Torx screws).
2. Install the new filter with fresh screws and gasket.
3. Clean the transmission pan and magnet thoroughly.
4. Refit the pan with a new gasket and torque bolts evenly to spec (~7–9 Nm).

Step 3: Refilling the Transmission

1. Locate the transmission fill tube (sealed from factory with a cap).
2. Remove the cap and insert a funnel with a long hose.
3. Add ~4.0 L of Mopar ATF+4 fluid.
4. Start the engine and shift slowly through all gears (P → R → N → D → back to P), pausing 3 seconds each.
5. With the car idling and transmission warm (approx. 60–70 °C), check level using a special NAG1 dipstick tool or by measuring fluid drained/refilled.

Inspection

• Fluid should be bright red and clean. Dark, burnt, or gritty fluid suggests overdue maintenance.
• Check pan magnet for excessive metal shavings — a light coating is normal, chunks indicate wear.
• Look under the vehicle for leaks around the pan and cooler lines.

Troubleshooting & Tips

• No dipstick? That’s normal — the NAG1 is sealed. A service dipstick tool can be bought online for accurate checks.
• Slipping or harsh shifts? Check fluid level, condition, and consider a filter replacement.
• Overfilled transmission can foam and cause erratic shifting — always measure carefully.
• Dispose of old ATF fluid responsibly at a recycling center.

Disclaimer: This guide is for general information. Always follow proper safety procedures and use the correct ATF fluid. If unsure, seek assistance from a qualified technician.