Oil pressure moving up and down with eng rpms
Asked by Brandon Aug 03, 2018 at 02:48 PM about the 2012 Jeep Grand Cherokee Laredo 4WD
Question type: Maintenance & Repair
2012 Jeep Grand Cherokee. 3.6L Oil pressure is
around 73psi when starting and then moves up and
down with rpms of engine. Once on the road for
about 5 min the psi goes to normal. About 42 psi.
But the pressure will still rise and fall with engine
rpms. Could this be a bad oil pressure sensor?
78,000 miles
12 Answers
Hornet_2497 answered 6 years ago
What you're seeing is pretty much normal oil pressure fluctuations. It's normal for oil pressures to rise and fall with engine speed because the pump runs at same speed as the engine. Also, when the motor oil warms up, oil thins out and produces less pressure being less viscous. Volume of flow may actually increase, that's good because oil cleans, lubricates and cools internal parts that get the hottest. Just be sure to keep the oil level up to normal, use the recommended viscosity, preferably a synthetic and you should do fine with regular oil changes.
What if its around 37 or 38 psi
Hornet_2497 answered 5 years ago
Ronald. Yes, 38 psi would be fine at idle speed and highway speed in virtually all engines. If pressure goes too high, there is a bypass valve built in to keep maximums at about 80 psi. I've seen some warmed up engines do fine with 10 psi at idle speed. On high mileage engines I've gone from 10w/30 to 10w/40 to increase oil pressure by increasing the hot oil viscosity. I've never ruined an engine yet and had some go over 300,000 miles with frequent oil changes. Smooth and quiet, they run well.
Hornet_2497 answered 5 years ago
Engine oil pressure of 96psi is not normal at all. It can be caused by running oil that is way too thick, especially in cold weather. It is most likely a failing oil pressure sensor that is giving a false "high" reading. There is also a pressure relief/by pass valve that is stuck shut or clogged. Make sure you are running the correct oil filter as there is a pressure relief valve built into the filter. I had an older vehicle give a reading of 100psi for a brief moment, and I figured a chuck of sludge plugged the pump output for a second. Yes, it had me worried.
Oil pressure is at 28 at idle
Hornet_2497 answered 5 years ago
Oil pressure of 28 psi at idle, warm or cold, is very good. I've seen older diesel truck engines with 10 psi at idle speed and they were fine....25 would be better.
Heather012 answered 5 years ago
I have an 03 jeep Cherokee laredo and we just put a newer/used motor in it and my oil pressure gauge keeps fluctuating from half to low and my check gauges light comes on I've already replaced the oil sending unit and.the oil pump why is it still doing it?
Hornet_2497 answered 5 years ago
Check your oil level. The six (4.0 liter) and the V8 (4.7 liter) both hold six quarts of oil. The recommended oil for the six is 10w-30 and for the V8 it's 5w-30. If this used engine was all sludged up, the return flow journals (holes) may be clogged up and the oil may not returning to the pan fast enough to satisfy the oil pump and it's sucking up air bubbles/not pumping smoothly. The V8 was known to have undersize return holes, so maybe there's a sludge problem.
Thats why 99% of all vehicles uses a light indicator instead of a gauge. If I monitor my blood pressure every 2 minutes I would certainly die of worrying alone.
so what about a 2013 only having used conventional 5w20 per MOM, and shop put in semi synth of 10w30 and now my oil pressure gauge is up to 90 at cold start and until warm is 70-80 accelerating and down to 38 once warm and driven 5-7 miles or 25 minutes? is this normal or is this a pressure relief valve issue?
Hi, i have a question and ill be very grateful if you could help me, i have a jeep grand cherokee 2011 3.6 v6 and it has over 180k miles i been using the 5w30 oil but i don't know if i should use 10w30 because it has been burning the oil pretty fast and it gives me oil pressure sensor all the time! Thank you
