We travel a lot
in the summer on the highways to get to our camping destinations.
This can be hard on a 40 year old vehicle. The typical
speed of traffic on the highways here is about 120km/h. For a
vehicle that was only designed to go 95km/h, this can be a poser.
On a hot (for Canada) summer day the UniMoG cannot travel at a
sustained 90km/h without the transmission overheating. Sometimes
80km/h is too much for it.
Our observations are approximate, because we didn't have an outside
thermometer on the truck yet, but here is a summary of our
Below about 20 degrees Celsius, the transmission seems to be able to
Between 20 & 30 degrees Celsius, about 80 km/h is sustainable.
Above 30 degrees Celsius, you can't get much more than 70 km/h without
If the outside temperature is above 40 degrees Celsius, it is time for
a siesta! You & the truck will both appreciate it.
This knowledge comes from using Amsoil synthetic gear lube and a VDO
temperature gauge. The temperature that we use as a maximum for
the transmission oil is 110 degrees Celsius. This number is
somewhat arbitrary, is come from some research that we have read on
the breakdown of engine oil. If anyone can ever tell us a BETTER
temperature to use (with appropriate documentation) we'll be happy to
The MOG can climb a hill in 1st or 2nd all day
under full throttle, but can't take high speed. Let's all
remember to stop and look at the view periodically on those hot days
for the MOG's sake. This has also led us to the theory that a
larger engine like the 2.8L M 130 for more power on the hills would be
just fine on the stock gear box, provided the driver keeps the speed