colenzae

I've changed the coolant a few times on my 2002 RX but would like to know if there are any quirks I need to be aware of before I attempt to drain and fill the engine coolant on my 2006 Highlander Hybrid. Bought it used and the coolant looks old. I ran into a problem replacing the rear brakes like I did on my other hybrids (2012 HS250H; 2006 Honda Civic Hybrid) and my brake actuator failed. So before I attempt anything that may on the surface seem like a simple task, I am going to ask questions first.
Thanks for all comments.....