'89 Olds (Cutlass Cruiser), 75K miles, been serviced regularly. The oil
pressure seems to drop sometimes down to 10-20 (almost in the red). We
check the oil every week (or every fueling) and keep it up all the way.
It never used to do that. It always stayed around 60 + or - 5. When we
start the car, its usually around 60, but sometimes it drops almost
into the red, but hasn't yet. Could it be the oil pump is failing? Or
could it be the gauge?
Thanks in advance.
Maybe worn bearings (actual low oil pressure)
dirty oil pump pickup screen
bad sending unit
Test gauge by removing sending unit connector and grounding it to block for a
few seconds - ignition on - while an observer in the car looks at the gauge. If
the gauge swings all the way over, it's good; anything else, it's not.
Next step would be to check hot oil pressure with a mechanical gauge. If the
mechanical gauge shows good pressure, replace sending unit. If hot oil pressure
fluctuates same as the original gauge, drop pan & clean oil screen, check main
bearing clearances, then (if bearing clearances OK) it may be that a new oil
pump is needed.
If it needs it, you can clean the oil pickup screen and the crud in the
bottom of the oil pan by replacing crankcase oil with GOOD carb cleaner, let
it soak 2-3 days, drain & replace with oil(including filter), drive 5-15
minutes to get it hot, and then change oil-&-filter again. DO NOT START
ENGINE WITH CARB CLEANER IN THE ENGINE!!! Hth, & good luck, s
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