I wasn't able to find any posts dealing with the 1HD-T (HDJ81) regarding what the proper coolant level should be and when to check it. I also looked at the FSM for the 1HD-T (page CO-3 and CO-4) and couldn't find any more elaboration on this... So, when I check the coolant in the plastic reservoir tank (i.e. the tank with the 'Full'/'Low' lines on a semi-translucent white plastic tank connected to the radiator) when the vehicle is cold, the coolant is an inch or so above the 'Low' mark. I then checked the radiator by taking off the radiator cap and the coolant is pretty much to the very top of the radiator at the base of the cap. We have not had any issues with cooling/heating at all, so this is a basic maintenance question. The coolant was recently changed to Toyota Red back when I bought the vehicle in November of 2016 by Land Cruiser's Direct. My question: Should I just add coolant (when the vehicle is cold) to the plastic reservoir tank up to the 'Full' level and that's it? Thanks!!