The gauge was probably reading inaccurately before because if your engine would have toasted it's main and rod bearings by now if it were truly running at 5 PSI at idle and 25 PSI at speed.
My 1977 Pontiac has the same type of oil pressure gauge as an FSJ....meaning jumps everywhere and is unreliable. I learned to basically ignore it. Normally it read about 40 PSI on the highway. One day it gradually dropped to 0 PSI in the span of a few miles, or about ten minutes. The whole time I was thinking, "either my engine is failing and actually loosing oil pressure or the gauge is failing...I bet it's the gauge"......so I kept driving with a little twinge of fear for the possibility that it may actually be real. It wasn't until the engine temperature shot up and I heard AND FELT the knocking that I realized the gauge was actually right.
I spent the next several months rebuilding that engine. It destroyed every main bearing. Wiped them out clear into the steel backing and trashed the crank too. Each bearing dropped the oil pressure as it failed. They failed one by one, dropping the pressure in incremental steps, until the last bearing failed and the pressure went to 0. The shame is it only had 7000 miles on it since the last rebuild when it happened and it wasn't the engine's fault. Misalignment to the transmission over those 7000 miles overloaded and slowly fatigued the bearings. They just chose that day to finally die.
I was 1000 miles from home on vacation when it happened. I towed the car all the way home behind a rented Uhaul truck. It sucked. The car won 1st place in it's class at a concours two weeks before. Now it had the ultimate shame: getting dragged home behind a Uhaul.
Having an oil pressure indicator THAT YOU TRUST is important. I don't care if it's a gauge or a warning light. The point is that you believe it and trust it.
'72 Jeep Wagoneer Custom, 360 V8
I love how arguements end as soon as Ristow comments. Ristow is right...again.
Last edited by FSJunkie : 10-14-2018 at 03:30 AM.