I had put this on SCOF recently, will re-post here. I agree with Rick, but i never have had any sort of problems with my own Canton unit. I always pre-lube, even if only had my motor off for several minutes.
begins:
have had the two quart model with the standard electrical switch for some years, i have the switch on a light toggel mounted on a small panel just below my dash. So i can discharg it when i want to.
I did not have room for the three quart model. Here is what i have learned, and how i use mine.
First, when checking my sump's dipstick, i first rev or idle my motor to put my A'sump to 60 psi, which is my engine's cruise hot
oil presssure. I then open the hood and verify on the A'sump's pressure gage that it is indeed at 60 psi. That way, when my engine is at cruise RPM, my A'sump is filled, ready for discharge. If your engine is low on
oil, and you assume your A'sump is filled, when it is not, and it has put 2-3 quarts of
oil into the engine's sump, and your dipstick reads "full", then when you start your engine, it will immediatly pull that much oil out of your sump and put it into thte A'sump, making your engine's sump that low on oil, unknown to you. I found this out by accident, so i always verify that my A'sump is fully charged before i assess the quantity of oil in the engine's sump.
Second, i always pre-lube for several seconds, on my car, the engine oil pressure will rise to about 20 psi, and then bleed down, quickly or more slowly, depending on how hot or cold the oil is. Whe it starts to drop on the engine's gage, i start my motor, and let it idle until i am sure all the things inside have fresh oil, before i give move my car under its own power.
I leave my A'sump "on" when driving, indicated by my lit switch (from Radio Shack), so that should my motor suddenly need oil for a few moments like when i sheared a distributor drive, it is ready to give me several seconds of oil to the bearings while i try to figure out what just happened.
When i am nearing home or a destination, i flick my A'sump switch off, so it is fully charged for the next engine start up, if the oil is hot, i will briefly rev my motor as i pull into my garage, to make sure it is filled to my standard of 60 psi, then turn off the switch before I let my motor idle down for shut down.
When i am on the track, and review my track video, I watch my oil pressure gage in the corners and under hard acceleration. I have a road-race Aviad pan, well baffelled with trap doors and such, but on some long corners, the cornering forces can put lots of oil up into the valvecovers, perhaps leading to oil pump pick up starvation, and i can see my oil pressure suddenly drop to around 40 psi, then stabilize there as the A'sump dumps its oil into the oiling circuit. The pressure then rises as i accelerate at track-out.
To me, the most important thing with an A'sump is that a refill never significantly reduce the oil pump's output to the engine itself. I would not want a fast refill to the A'sump, taking away oil that is better sent to the mains, i much prefer the theory that oil preferentially goes first to the engine, then more slowly fills the A'sump. The only potential unwanted side effect of the slow refill of the A'sump is that my engine for a few seconds has an overfilled crankcase, possiblly leading to frothing of the oil from the crankshaft, not necessarily a good thing. But with a smaller A'sump capacity, it is less than a three quart model would cause, and I still think the engine bearings need oil before the A'sump gets it.
In summary, oil first to the motor, then to the A'sump. I think a switch is vital to being able to reliably check the engine's dipstick, or you won't know how much oil is where in your system.
My own A'sump and electric switch has worked reliably for some years. There is a picture of my car in the Canton catalogue, by the way. I sent one to them, they put it in their catalogue several years ago.
I use one of the no bypass long canister replaceable element Mecca oil filters on my Jag.
Anyway, if you use an A'sump, i think you need a precise set of standards of how you check your oil level, and how you use it to suit your needs.
All the best,
Hal, in ole faithful #672