I bought a 2006 Tundra without the tow package. I now want to add a transmission oil cooler to the front of the radiator. I understand that they are not very expensive and are usually easy to install. Has anyone done it? Do you have any pointers? My main concern is that the 2006 has a sealed system so how do I add the fluid needed for the increased capacity and check the fill level afterwards with no dipstick on this vehicle. I know I will lose some fluid in the process and want to maintain the proper level. Thanks for any help!