Also, it tends to fluctuate. So it'll go right up, then cool down a bit and then go back up, then down etc.
That would definitely indicate that your fan is working then I reckon, though you might have a faulty thermostat. Both fan and thermostat are cheap fixes (especially if you use parts from wreckers) for engine overheating and proably the most common cause apart from low coolant/oil levels.
My engine doesn't overheat as long as the coolant and oil levels are topped up (as you would expect).
I have same issues. In the last few months I have had increased oil consumption as well as a loss off coolant. Coolant is disappearing at a faster rate than oil. Both are showing no signs of leaks except for the loss in levels. I am assuming that the two issues are not related at all.
About the time my oil consumption increased I had just taken off and re-sealed my rocker-cover gasket (head gasket?) because I was having visible oil leaking from engine and dripping onto ground overnight. Fixed that, no more visible leak but now oil is disappearing faster!!?!??. No smoke (blue or otherwise) from exhaust, no oil on ground, no leaks to be seen anywhere around engine exterior. Really VERY confused as to where my oil is going. Topping up oil every few weeks - month with 1-1.5 Litres, much more than before.
Can't find any sign of coolant leaking, but as someone said it is probably evaporating as steam while driving and then not coming out when the system is not under pressure. Tried running the car in the driveway to see if I could find anything, but nothing apparent. Where would a leak be most likely to show up (radiator, pipes, air con, etc.??).
My car is a 156 2.0L 1.6V TS, Yr: 2000, manual. Owned it for about a year. I think the oil I use is 10W40 (Live in Australia) well known brand. Been topping my coolant up with water only due to amount of coolant loss. Mechanic said it was fine to do so temporarily but it has been a few months now so I need to top up with coolant and sort this issue.
Any ideas would be greatly appreciated.