Once the lines are disconnected from the radiator, there is no flow there, just plug the ports.

 

There is a oil filter adapter that has no cooling lines. I ran a standard SBC filter adapter for awhile but I had headers, don't thing a standard SBC filter would clear the catalytic converter.

An L99 with in radiator oil cooler sounds like an odd duck, mine actually came with the cooler-less adapter.

 

I think I misunderstood how this cooling setup works. So, it doesn't use coolant to cool the oil?

Why I thought it went out in the first place is because my coolant is polluted with engine oil, the whole cooling system is filled with thick brown sludge. I drained the oil and it was clean or as clean as 2000 mile oil is. The engine sounds like it runs fine, I assumed it wasn't the head or ghead gasket. From what I've read the oil coolers seem to be the culprit on LT1s. Could it be something else? What is the likely hood something happened within the radiator?

 

The f-bodies had a setup that ran coolant to the oil filter adapter, the b-bodies used either a cooler that ran oil into the radiator or a separate cooler mounted in front of the radiator both of which had the oil flow away from the engine.

If you get a leak in a tranny or oil cooler in the radiator the oil or tranny fluid can push into the radiator when the engine is running BUT soon as the engine is shut down both of those things go to zero pressure while the radiator stays pressurized till it cools which means coolant would backfeed into the oil or tranny fluid.
Could someone have mixed green and orange coolant in your car? That makes for a nasty sludge.

 

I did a complete radiator flush last year. It had green coolant before and replaced with green coolant. When I first thought I had a problem it overheated. I thought maybe thermostat and I pulled it out and there was oil sitting right below it in the water pump.

 

maybe the leak is so minor the coolant backfeeding to the oil is getting boiled out?

How long are your trips on average and is there any yellow goop under the oil cap?