I just started my engine after installing a new oil pump and front oil cooler. Everything seems to be running fine however when I stopped the engine to check the oil level- I noticed a borborygmi type sound from the from of the engine for a few seconds. Checked my oil level and the oil was very frothy.

Oil pressure was great, no oil leaks, everything seems to be running fine. The car had been sitting for about 2 weeks while I was installing the new cooler. The oil level is normal. I did not have any oil in the hoses to the front cooler whcih is why I am checking my oil level closely since it will obviously drop once the thermostat opens.

FYI- My new setup uses a schadek 30mm pump (yes it was modified), mocal sandwich plate with built in thermostat, rx7 front cooler via AN12 braided stainless hose.

I used Brad Penn 20w50 oil however there was probably a quart of Amsoil 20w50 (high zinc) oil already in.

What causes the frothy oil?

I was told it's from the oil not getting hot enough on short trips to burn off he water vapor (condensation?) . I used to drive a 5 mile trip to work and it was there. Later a 30 mile trip to work daily and never saw it again.

bor·bo·ryg·mus (bôr b -r g m s). n. pl. bor·bo·ryg·mi (-m ). A rumbling noise produced by the movement of gas through the intestines.

I didn't know how else to describe it. I listen to people's bellys all day long so that's what's in my head.

Hopefully nothing is inhibiting the peristalsis of your lubricating system then.

The name was coined as it sounds like what it is. I knew what you meant. Was your system totally purged of air?

I was told that we should fill the front cooler lines with oil before starting it.
For that reason, I plan on putting at least one tee in the lines at the highest point with a cap so I have a port to fill it and purge the air out.

You need to pre-fill the lines and cooler ...

So what is the best way to purge the oil system of air when the front oil cooler is already installed?

Would this work?

Remove the rocker panel. Cut the stainless hose on the return side (going away from the cooler). Fill the cut hose that returns to the engine with oil then put the end of that hose in a bucket of oil. On the cut side of the hose that comes from the cooler- put that in the bucket also.

Turn the starter (but don't start the engine) until the hose coming from the oil cooler starts pumping oil through it. Then install a coupler and reconnect the hose.

Am I way overthinking this?

Yepp. No need to cut anything. No need to run the engine or pump.

Gravity is your friend ...