So now that we have covered the basics, let's go one step further. That is why your trans fluid will come out of the transmission hot and in 12" be cooled by the coolant enough to return to the transmission. If you accept that reality, then you understand that your coolant in the radiator is less than 180. If you don't believe me, take out your T-stat and see how much cooler your engine runs. It slows the coolant down so that only enough coolant re-enters the engine to maintain 180 degrees. The engine modulates it's temp by use of a thermostat which is hardly ever wide open. It decends thru the radiator and cools well below the 180 op temp of the motor. So the coolant enters the top of the radiator heated by the engine. I've been able to monitor this effect on other cars I've had with a diagnostic interface and always had to restore the radiator cooler because the transmission temps would soar above 220 degrees with just an aux cooler alone. The B&M cooler can only lower the oil temperature by 20 degrees +/. So by adding the cooler inline " after" the radiator, you bring the temp up quickly using the engine coolant, but then keep it down below 160 degrees by cooling it again through a 2nd cooler. The radiator is typically at 180 degrees. Why then add a cooler to the transmission line? Because the optimal temperature for a transmission is around 160-180 degrees. If you overheat the transmission, it will die quickly. A liquid to liquid cooler is far more efficient than an air to liquid cooler. Second, it cools the transmission better than just an air-cooled aux cooler can do. It warms the trans fluid to operating temp quicker than the transmission can do on its own, which help prolong its life. The radiator cooler serves two functions. now also add the extra B&M aux cooler, but do not just bypass the radiator. First, just spend the $120 to buy a new radiator. I keep reading posts here where members are encouraging people to just by-pass the radiator transmission fluid cooler to avoid the strawberry milkshake problem.