HI everyone, hope you all had a good xmas. I went away to Coffs Harbour. Didn't do any 4wd but went on unpaved roads to reach campsites.
Yesterday I drove back to Brisbane, a 450ish km drive on which I drove most of the time 110ish km/h. Did it in 3 pieces with some 10min breaks. On the last bit, i stopped for fuel and noticed suddenly a lot of coolant disappearing out of mine outflow tube (the tube that clears it onto the road). Checking coolant levels, all seem to be fine, although hot but not boiling. This didnt worried me so I continued to drive the last 50km home. The temp gauge moved a couple of times between 1/3 and 1/2 but never further than 1/2way. Today checking the radiator and coolant bottle, both seemed very empty (eg. I could not see anything in the coolant bottle and radiator). I had to top up the radiator with 4 liters! and the coolant bottle as well. I wasnt parked level, but with front down but still expected to see sufficient in the radiator. There is nice flow through the radiator when the car is started and the hoses look fine.

Bit of history about the car. I bought it a while ago for a big lap which I am planning to do next year, it is my first car and I dont know much about engines so used this forum a lot to gain some knowledge. The car is awesome and it is amazing to just be able to drive on the beach etc (we dont really have that in the Netherlands).
I had on bribie some overheating issues (see an earlier treat) , which I solved with the help of a mechanic by replacing the viscous fan and thermostat. After that I had no issues anymore besides one time on a very hot day where my LPG wouldnt start right away but after four times (see another treat), but this was discarded as extremely hot weather.
Yesterday wasnt a really hot day, it was rather cool and it was raining a lot. I was running on LPG and doing 110km/h most of the time.
This kind of worries me that there are still some problems out there and I want to prevent to encounter a blown engine in the middle of no where on the big lap.

Anybody any advise?