Not_Sure

can anyone clarify: I installed a larger oil cooler. Is there or is there not a thermostat that controls oil flow to the oil cooler? as Im wondering if it has filled with oil or not? I havent driven the car much and/or very hard as im still chasing other bugs.

I think i put 8qts in after putting in the new oil cooler. (its about 3x the stock size)

CHD

I think this is the only thermostat for the oiling system. It's on the upper oil filter housing. The lower cooler doesn't have a thermostat. Fully filling mine when the lower cooler had been off the car and drained was 7 qts., so about 8 qts. or so with the larger lower oil cooler seems about right.

Not_Sure

right ok so, just to confirm there is constant oil flow through the cooler?

944M3

https://rennlist.com/forums/944-turb...hermostat.html

It keeps oil out of cooler until it reaches operating temperature.

I had one fail and if remember correctly, at startup the car never hit 5 bar oil pressure at idle After replacing it, the car starts at or close to 5 bar at idle. When the car warms up the pressure drops to about 3 and then rises with revs as expected.

Someone please correct me if I’m wrong but I believe that behavior is controlled by the oil thermostat.

Oddjob

Agreed, if you added 8 qts, it likely filled the oil cooler.

The cooler is always filled with oil, but oil only flows when warm enough for the therm to open.

I'd guess the pressure drop is some combination of temp rise of the oil and the viscosity dropping with that temp increase, in addition to some increase in system pressure drop as the oil is pumping thru the cooler (when the therm opens).

But that said, N/A's without the external air-oil cooler have similar pressure drop when the oil gets hot, and I've added both larger and dual coolers in series and haven't noticed significantly more pressure drop than with the single stock cooler. And the oil pressure is affected by oil weight, as 15-50 will maintain higher pressure @ hot idle than say 5-30. So point is, I think the pressure drop has more to do with oil temp viscosity than the oil flowing thru the cooler.