The bottom of the tank is cut on an angle and an AN#6 fitting welded on at the lowest point. This will have a cap on it. It's positioned so you can just put a pan under the car and it will drain straight into it (no chassis parts in the way). I thought about plumbing it back into the motor but figured a drain was a lot easier. If it was a daily driver car I'd probably plumb it back in.
Where does the
oil go? Well the two pipes on the top of the valey plate take air from the crank case and rout it to the breather tank. There's a baffle setup inside the breather tank that helps to seperate the
oil mist out of the vented air. The seperated
oil collects in the bottom of the tank. You would check the level from time to time by removing the filter on the top and having a look inside and draining when nescecary. Phil N reckoned he collected about 300-400Mls over the nationals in his setup.
Normally this venting would be ducted back to the air intake of engine. Oil vapor would be burned along with the fuel and air. One of the side effects of burning this oil is that it drops the octane rating of you fuel air mix. That oil also cokes up the inside of your engine over time.
Cheers