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This is absolutely not true. At the same pressure and rpm on the same engine, a high volume pump will put exactly the same amount of oil to the engine as a stock pump, and that same amount out of the pan. The "suck the pan dry" theory has been around for years, but has been untrue for all those years.



How do you figure that? Per revolution the HV pump is pumping more oil than a standard pump. The excess goes out the pressure bypass. More is being pumped out of the pan, but it's cycling right back into it. Some claim the worry is that if your engine clearances are nice and tight and if your bypass valve cannot flow enough oil. you run the possibility of running oil pressure over 75psi, in which case you would displace more oil from the pan to the bearings, etc. But IMO the bypass valve is up to the task.

In reality I think the HV pumps were developed as a band-aid to engines with worn/loose bearing clearances to maintain an acceptable amount of oil pressure.