Doing the 48,000 km service yesterday, and when checking everything noticed the engine coolant overflow bottle was almost empty. MAJOR PROBLEM! There is no sign of leaking, so I presume it evaporated or it was never filled to the full mark from the factory. Man, that level is hard to check. It's dark down there! I may mark the passenger side end of the overflow bottle. Much easier to see the level there. Had to buy the full "gallon" of "Super Long Life Toyota Coolant", for $20. I only needed perhaps 1/2 litre. Has anyone else noticed coolant loss, presumably from evaporation? This was after 3 years of operation/48,000 km or 30,000 mi. The inverter circuit is fine. No loss in it.
That amount of coolant loss is unusual after 30K miles. Did you remove the black plastic cover over the radiator to access the radiator cap? If not I suggest that you do so, so that you can remove the cap and see if the radiator is full or also needs fluid to be added. I also recommend that, once you've checked that the radiator and the overflow container are both full when the engine is cold, that you periodically check the overflow container. If the level drops noticeably, look for a leak at the hoses, the radiator, and the engine water pump.
Well, it's been a while since I filled the tank correctly. The level has not changed. So I suspect I am not loosing coolant and that the system is full. As I said, it's difficult to actually -see- the level in the overflow tank. I -assumed- when I bought a brand new car three years ago that Toyota Motor Corporation and the accredited dealer would have checked fluid levels and set them as required during the PDF that I paid $400 for. So I also -assumed- that what I saw in the tank was the correct level. I guess I was too trusting. As I recall, the level has always been that low, and only now did I realize that. So much for "dealer service". Good thing the car has not been back there!
It's good to know the car seems OK so far. It's good practice to check all fluid levels once in a while so we get early warning of potential problems. I also find the coolant level difficult to see but if I shine a strong light through the translucent container to light up the fluid and look from the other side then I can get a good view of the level. Hope this helps. Good luck!