Opinions. My mazda b2200 had always read low on the temperature guage from newi thought it was a sensor and didnt worry about it

My Mazda B2200 had always read low on the temperature guage from new.
I thought it was a sensor and didnt worry about it.
It was due for top and bottom radiator hoses to be changed, so I had a look at the thermostat as well, and bugger me it has been stuck open for years.

After the thermostat replacement the temperature guage operates normally.

The question:Will fuel economy be improved significantly!

I know that it would make a big difference on a car with electronic engine management as it would tend to run rich because it wasnt up to temp.

This is a points and carb motor with automatic choke which used to drop down to a proper idle just like it should.

Whaddya reckon!

Fuel economy should improve as the oil will flow better, but I doubt it will make a lot of difference.

you could also argue it will improve due to better atomisation of the fuel now the manifold will reach proper operating temps, you may well be having to cut the idle back a bit now, and you will use less foot to maintain motive power
it is often stated that 10% improvement can be due to proper temps and tuning - how much of that is temps though, not sure, expect some improvement

Cant say much for the servicing this vehicle had from new then, running cold all the time will cause premature engine wear, this should have been picked up during servicing.
If as you say you have had it since new, surely the anti-freeze should have been changed since then and who ever changed it, should have had to get the engine up to temp to check the radiator levl.
Very poor servicing IMO

Not apples with apples, but my 89 nissan van had a stuck thermostat, before replacement about 400km per tank, after replacement about 450km. paid for itself in a couple of weeks :)