The oil temp on my 04 st170 has suddenly started playing up the oil pressure is fine but the oil temperature goes down when driving it stays constant when ticking over at half way has anyone had this problem is there an oil temp sensor on the st170 and if so where is it if not how does the oil temp gauge get its it's signal

 

I have a 2003 focus st170 and I have the same thing happening but I just thought that when in traffic or town driving it sits constant at half way the same asthe engine temp but when I get on a good sstraight road the engine temp starts to drop and oil temp goes down near the bottom but I just took it that it was just the cool air blowing through the engine.So I never thought of it as a problem.If u find out there is a problem post it up so I no aswell.

 

That's your thermostat, had the same issue and the thermostat was jammed open so when on a run it was making the engine cool.

 

thermostat, 5 minute job on st170, small tray under the housing to catch the half litre of coolant that will come out, then pour it back in the expansion tank. job jobbed.

 

My oil and water temp kept dropping down to cold when wires on coolant temp sender broke.
The car ran lumpy as well because ECU thought engine was cold.
New coolant temp sensor fitted and water temp juust over half and oil temp at half all the time when warm.
I dont have the 'modine cooler' in mine any more as it sprung a water leak, so i bypassed it.
Hope that helps?!
Cheers
Kevin