I have a 1996 discovery es 300tdi, currently living in spain 12 miles from coast but 910 metres above sea level, the transmission hot light comes on approximately half way up the hill (500 metres in altitude)when towing a 1 tonne trailer (the light comes on at 650 metres without the trailer). The temperature is usually about 30 degrees C. Is this normal, I have changed transmission oil but not much change. Do I need a larger oil cooler or is it likely a transmission overhaul? The red light doesn't go out until i get home and let it rest, the last mile having 200 metre height gain and no tarmac.
Any help much appreciated.
