I have a 2012 LS 460 AWD with 70,000 miles that I purchased in August. In December I noticed I could not get heat while in park, despite the engine being hot and having fine heat while driving. I checked the coolant and noticed it was just below the low-level mark, topped it off which fixed the issue. Three months and 2,000 miles later, same thing, heat disappeared while in park, checked the coolant and it had dropped down to just below the low level. What could be causing the coolant to drop from full to low every three months and 2,000 miles? I don't mind adding coolant a few times a year but I'm worried there's a bigger issue (head gasket, brake actuator?, etc.). If anyone has any ideas for what it could be and what I should do I would really appreciate it! Thanks!

 

Gasket? Yikes. What does the underside of your oil cap look like?

 

Maybe it's the notorious valley plate leak. Have you checked the seams on the top of the radiator as well as the hoses?

 

Check the radiator and the water pump for leaks. If it is clean, it is most likely a valley plate leak.

 

Looked in today, almost embarrassing I didn't notice before, big drip coming from a hose right above the coolant reservoir, should be an easy fix (phew). Thanks for the input greatly appreciated!

 

Yeah that's kind of obviously but it happens. Make sure to clean up ALL the pink residue and keep an eye on it after you figure out if it's the clamp or the hose.