When Chrysler introduced the New Automatic Gearbox Gen 1 (aka NAG1 or WA580) five-speed transmission in the 2005 models, it left many DIYers lost when they discovered there wasn’t a dipstick for the transmission. The dipstick tube had a screw-in plug rather than a dipstick and sealing cap. The dealership techs used a specialty tool dipstick (MLR-9336a) and a factory scan tool to monitor the transmission fluid level and temperature.

Now that the NAG-equipped platform Mopars (2005-2012) are getting long in the tooth and are possibly owned by a second or third owner, these cars likely won’t be visiting the dealership for service. To monitor the transmission’s fluid level, B&M developed a billet steel and 6061-T6 aluminum locking dipstick (part nos. 22300 – 3.5L and 3.6L, 22301 – 5.7L, and 22302 – 6.1L and 6.4L), which slips in place of the factory dipstick plug. Seeing we do our service work, we thought this dipstick would be a great addition to our NAG-equipped 5.7L Police Package Charger, so we picked one up from B&M.

Top Left: The NAG1 5-speed transmissions came stock with a plug in the dipstick tube rather than an actual dipstick. B&M’s dipstick allows the fluid level to be checked without the need for a factory specialty tool. Top Right: The B&M dipstick has fluid level indicators for a low and normal temperature range. Both ranges offer precise fluid measurements, but B&M recommends checking the fluid with the NAG1 at normal operating temperature. Bottom Left: The factory dipstick plug is located at the rear of the engine behind the engine cover (green arrow). Bottom Right: Upon closer inspection, the plastic plug has the words “For Dealership Use Only” embossed on it.

The B&M dipstick has a knurled grip and an etched logo on the screw-in cap. The fluid level indicator has a low and normal scale based on fluid temperature, both of which provide accurate measurements. However, B&M recommends checking the fluid level with the transmission at normal operating temperature. The dipstick has an overall length of 33.8-inches, and it comes with the sealing O-ring installed. Lastly, the dipstick is 50-state emission compliant for all vehicles and comes with a one-year limited warranty.

Top Left: The B&M dipstick cap is constructed of 6061-T6 aluminum with the B&M logo proudly engraved into it. The cap has knurling on the edges, which provides an adequate surface to grip during installation or removal of the dipstick. Top Right: The O-ring on the B&M dipstick required lubrication to allow it to slip into the dipstick tube. Bottom Left: After removing the plug, we slipped the cleaned dipstick into the tube. Bottom Right: Upon completion of a 20-mile drive, we returned to the shop to check the fluid level. With the engine running, we removed the dipstick by gripping the knurling on the cap.

Over the years, we have done several tech stories, and this one ranks close to the top of the list of easy tech. We popped the hood, located the factory plug, removed it from the dipstick tube, cleaned the new dipstick (to remove any packaging material), lubed the dipstick cap seal, installed, and locked the dipstick in place. Just like that, we were done with the installation. The lube on the seal was essential because the seal was a tight fit inside the dipstick tube. We used fresh ATF+4 for the lubricant.

Left: We pulled the dipstick from the tube. This is the same process that would be used with any dipstick. Right: When we checked the fluid level, we were satisfied with the dipstick measurement. The fluid was in the normal scale at the top of the indicator range.

Above: The B&M dipstick cap provides a more appealing appearance in the engine bay than the factory plug.

We followed the instructions, which suggested the Charger be driven for a twenty-mile cruise. When we returned to the shop, we slowly ran the gear selector through all the gears before engaging the transmission into Park. With the engine still running, we checked the fluid level on the dipstick’s indicator, and we were at the top 80°C (176°F) indicator allowable range with a warmed-up transmission.

If you are an owner of a Mopar with a NAG1 and are interested in knowing the fluid level status, B&M has the locking dipstick for you. For more information, click over to B&M, or to find a dipstick for your Mopar, check with your favorite auto parts store or B&M online. Once installed, B&M’s 65+ years of quality will show every time you lift the hood.

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