[Formulajones]

The answer really shouldn't be zero oil unless you prefer to add your own oil to the pump or you don't mind running the pump dry and chance shortening the life span. These vacuum pumps do rely/need a little bit of lubrication to keep them working properly and live a long happy life. How much has always been the question.

I personally prefer to have it pulling a pinch of oil, because frankly I don't want the added worry and maintenance of adding oil in the top of the pump every time the car is driven. Especially in a street driven application such as dad's car.

We experimented with dad's car for quite a while, moving the location of the suction line in different places, baffles, no baffles, pulley ratios, adjusting the pump vacuum up and down. He couldn't even drive the car from the house to Phoenix before the catch tank would overflow and spew oil all over the car.

It wasn't until we ran into Frank at the local cruise and he mentioned moving the suction line to the middle half of the valve cover and at the very top. I didn't even think of that spot. Once that was done, we found it didn't even need a baffle. He actually drove round trip a little over 200 miles to Goodguys and back and pulled about 3-4 ounces out of it. That's with the pump pulling about 6-8 inches at cruise rpms and about 10-12 inches at peak rpm. Hell we could race it all day at the track and not even worry about it.
I'm comfortable with that, thinking it should be enough to keep the pump lubed. If we decide to reduce the amount I'm sure adding a baffle would slow it down more, but I'm not the least bit interested in cutting it off from oil completely.