DIY: Oil Pressure Gauge

spearfish25

I can tell you that the oil pressure gauge reads a constant 90-100psi even at idle when completely cold started. After about 2-3min, the idle pressure will start to drop to ~60-70psi and doesn't settle to 20psi until the oil is at 180F. When driving, anything over 2k rpm will produce 90-100psi oil pressures until you get up to the 180F oil temp range as well. It's dramatic...as the oil climbs to 180F, the pressure finally starts to fall. Once the oil is 180F or above, highway 2-3k rpm driving in 6th gear gives steady oil pressures in the 65-75psi range. Anything over 3k rpm makes the pressure climb to 100-105, especially WOT. My guess is the oil pump relief valves opens around 100 psi since I've never seen a pressure peak above ~100-105 psi.

Since installing the gauge, I'm much more cognicent of driving conservatively until my oil temps come all the way up to 180F. I'm also glad my oil cooler has a 200F thermostat instead of 180F. To answer your question, yes this still applies to you without an oil cooler. It just underscores the need for people with coolers to wait until oil temps come up to 180F before driving more aggressively.

__________________
2013 Cadillac V-Wagon, RIP Z

wstar

Good info, thanks . I always warm up anyways, but frequently I'm already on the road rolling slow by the time the oil hits 140, and at 160 I'll drive "normal", but not hard WOT stuff till 180+.

For those of you with coolers: if you have a thermo plate, you don't have to worry *too* much about pressure damage to the cooler when the oil isn't fully warm. Based on my conversation with the MOCAL guy a while back (who made my thermo plate), the design of the thermo is that both pathways are fully open when the oil's cold. The bypass (that skips the cooler) gradually closes off over a ~5-10 degree range centered on the thermo plate's temp rating. Meaning even with a 180 thermo, you don't completely lose the bypass until 185-190-ish, and by then the oil should be thin enough to be fine.

If you don't have a thermo plate, all that pressure is going straight to the cooler when the oil's cold, and I'd be a lot more careful.

__________________
7AT Track Car!
Journal thread / Car setup details