Put a transmission fluid temperature gauge in the dash knock-out alongside the ignition key. Westach 399DS from genosgarage.com. Temperature sensor is a tight fit at the end of the aftermarket dipstick. Heat shrink tubing was deteriorating in the hot fluid so I tied it on the tip with fine copper wire. The restriction is down at the pan level so it can be frustrtating but I did not want to cut into one of the lines. I understand later model MLs have factorty fluid temperature sensors but I did not have one to work with. The transmission will suffer a premature death if you let it get too hot. My gauge is yellow at 250F and redlined at 300 degrees F. but did not go over 225 degrees with my 2000 lb. tow as I crossed the Cascades. At 275 F, I'll pull the old jalopy over like "The Grapes of Wrath." I had manually activated those two huge fans on the front of the radiator. See: "ML Towing-activate factory radiator fans"

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