I would take to Dealer and let them change it at 100K miles and not worry about it cause per Toyota Socal it never needs changing but i know the manual says under extreme conditions change it around 60 or 90K but i would still let Toyota do this procedure since they have the proper fluid/evac machine to do job! Lotta people have their own procedues for doing this job but seems labor intensive and not sure if you might cause moe problems than ya might solve? Thier is a check procedure here on this forum under the adminitrators name and i will see if i can search for it, or just go to drivetrain and search transmission fluid check!! yep it is over there and it's a pdf file!! can't miss it!!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!