RU sure?
RU losing coolant - check expansion tank.
Not sure of the prevailing weather in your neck of the woods but even rain has to be boiled off if it gets into your radiator matrix - this will have an 'engine smell' unless radiator is fairly new.

Mark your expansion tank when cold and then at operating temperature with a strip of masking tape at each level - then you can check daily easily.

Good luck

__________________
NormanB
230 TE (W124) 1989 with 153,000 miles on the clock - hoping for at least another 100K