8.1 Oil Pressure and Filter
Last oil change I installed a Fram Ultra Guard since the Wal-Mart by me stopped carrying AC Delco filters. Local auto parts stores don't seem to carry the AC Delco filters either. Right after that I...
Forum Discussion
Think of pressure as the resistance to flow. No resistance to flow (i.e. an open garden hose) = 0 pressure. High resistance to flow (a crimped garden hose) = high pressure.
The key is: Where is the pressure measured? Up-stream or downstream of the filter? My guess is that, since the Fram ran at a lower pressure, the pressure sensor on your engine is upstream of the filter. (Fram generally flows more oil, hence less restriction and lower pressure). Low pressure doesn't necessarily mean low flow or a bad oil pump. It may simply mean that the filter flows more oil.
At work, we measure pressure drop across the filter to determine when it's clogged and in need of a change. Engineers far more skilled than I am did the calculations and have determined that at XX GPM flow rate, the pressure drop across a new filter should be XX psi, when it's 75% clogged, it will be YYpsi, and when the filter is 'clogged' the pressure differential should be ZZ psi. Note that under all these conditions, the same amount of oil is actually flowing through the system.
It's a little tougher to make that sort of determination on an engine though... The flow is constantly changing with engine RPM and load. If your pressure gauge always shows the same pressure regardless of RPM (and I know the OP's doesn't but many do) it's not truly measuring the pressure.
The key is: Where is the pressure measured? Up-stream or downstream of the filter? My guess is that, since the Fram ran at a lower pressure, the pressure sensor on your engine is upstream of the filter. (Fram generally flows more oil, hence less restriction and lower pressure). Low pressure doesn't necessarily mean low flow or a bad oil pump. It may simply mean that the filter flows more oil.
At work, we measure pressure drop across the filter to determine when it's clogged and in need of a change. Engineers far more skilled than I am did the calculations and have determined that at XX GPM flow rate, the pressure drop across a new filter should be XX psi, when it's 75% clogged, it will be YYpsi, and when the filter is 'clogged' the pressure differential should be ZZ psi. Note that under all these conditions, the same amount of oil is actually flowing through the system.
It's a little tougher to make that sort of determination on an engine though... The flow is constantly changing with engine RPM and load. If your pressure gauge always shows the same pressure regardless of RPM (and I know the OP's doesn't but many do) it's not truly measuring the pressure.
