My temp gauge reads round about 70 all the time, it has done for ages and I've never really given it a thought. The (diesel) engine seems to run fine and the heater works etc. What do people think is the reason/best course of action?

I used to have an 1.8d escort van which had the incorrect temp sender from a (1.6d I think), this made the guage read 'just below red' all the time, never overheated so didn't worry about it. Do you think something similar has happened here?

Might this be a thermostat problem?

I'm sure it's a thermostat issue. Recently replaced the one on my 1.6 for the very same reason. It seems that all Felicia's suffer from thermostat failiure at some point. Once thermostat was replaced the gauge read normal and the heater was even more effective.

I had a similar issue with my 1.6 truck. Replaced the thermostat, and fresh anti-freeze. Ran fine after that.

^ Ditto with Rainbow. Just replaced on Pick Up & temp restored