I live in South Africa and own a 1996 STI classic which has recently had an engine overhaul and aftermarket oil cooler fitted.
The oil temperature gauge indicates +- 240F and oil pressure gauge +- 40PSI at normal running temperature.
Engine check light is on but this could be a faulty sensor.
Fuel used is 95RON + NF octane booster (+- 5 RON)
Any comments / advice would be greatly appreciated.

 

If the pressure is ticking over then I'd say that's ok. The temp. is a bit hot for normal driving but presumably it's pretty warm down there in South Africa at the moment?

How recent was the rebuild?

 

Yep, that oil temp is high, it's around 115 deg C.
Mine runs 90 deg even in south of France thrashes, sometimes reaches 110 on a LONG hot motorway.

 

As said given that you have a cooler fitted that temperature is too high as a permanent state. First thing would be to make sure the gauge is reading correctly, then make sure your cooler is working as you think it should i.e. if it has a thermostatic valve make sure it's not stuck closed.

What rpm are you quoting the pressure at?

 

around 3000rpm

 

In which case the oil pressure is a bit low too.

 

the oil pressure will be lower if the oil is very hot as it will thin out.
do you have a thermostatic sandwich plate for the cooler?
mine opens at 85 and only really rises if in traffic with no airflow.

 

This.

What grade oil are you using? If it really is getting that hot you'll need to change it very regularly.

 

I am not sure if the oil cooler has a thermostat sandwich plate. I will find out.
I usually use Castrol 20/60 but, again, will have to check what the garage put in.
Thanks again for your assistance. I will revert when I have more info..

 

oil cooler is working ok. changed oil & filter - and oil still above 240F
and pressure low. Now changing oil pump!

 

Just re-read your op.

Is the car mapped for 95 octane? If not, I'd seriously think of getting it done.
Octane boosters have been shown to be pretty cr@p.........