what will cause low oil pressure on startup and idle but will get around 40 when the engine warms up 05 5.3 silverado


Asked by Dec 30, 2014 at 06:44 PM about the 2005 Chevrolet Silverado 1500 Z71 Ext Cab 4WD

Question type: Maintenance & Repair

13 Answers


How many miles is on engine and how low does it go, and how long has it been doing it, and how many my miles on your oil change, are you using the motor that is recommended in your owners manual or on your oil fill cap, and keep it full. Thank you Dennis

3 out of 3 people think this is helpful.

Is that actual oil pressure or just what the dash gauge is reading?

3 out of 3 people think this is helpful.

it has been doing this about month or so. oil is correct have kept it changed around 3000 miles truck has 175000mi. it will fall back and forth at idle and once you give it gas it will go to 40 and the warmer the temp the better the pressure. sending unit is new and checked pressure with a gauge it read the same

10 out of 10 people think this is helpful.

Sounds like the first sign of worn out bearings or oil pump. HTH. -Jim

1 out of 1 people think this is helpful.

You checked your oil pressure with a gage, good, you have 3000 on your oil, I would go ahead and change it, do this, get a clean glass bottle, with the engine cold, clean around the drain plug first, drain the first part of the oil into the glass bottle, let the glass bottle set, overnight, if any of the oil separates, if so that's not good, let me know the color, Dennis


have the oil change every 3000mi. just had it changed yesterday. I was thinking oil pump or screen problem . there shouldn't be any reason for the screen to be stopped up but you never know.

3 out of 3 people think this is helpful.

A Ford Bronco was in my shop with oil fluxuations cold and below 1500 rpm fully warmed up, replaced the oil pump and pickup screen and the problem went away, the customer wanted to know why it was the oil pump so I took it apart and found pump rotors badly scoured and a lot of clearance, so he was satisfied as it was totally visual.

2 out of 2 people think this is helpful.
Best Answer



Do you still have or can you get the old oil filter Thank you Dennis

2 out of 2 people think this is helpful.

I am having the same issue with my '05 Tahoe. Are you looking for coolant in the oil? Was this ever resolved?


To start with, were are you living, what state, are you having severe cold weather, be low or near o* fahrenheit, do you know what weight motor oil is in you car, how many miles is on your car/ if engine has been replaced or rebuilt, and how many miles has it been since your last oil change ? please check and advice Thank you Dennis dennisjf12@gmail.com


Be aware there is a small oil screen inside the hole below the pressure sender on many chevy silverado's. Remove the oil pressure sender, use a small pick tool to pull the filter from the hole, replace with a new filter. These tiny filters will clog, and cause low pressure warnings, and or wild variations in pressure as engine rpm's increase.

8 out of 8 people think this is helpful.

What ended up being the solution?? I have the Exact same problem on a 99 Silverado 5.3L. The colder the worse it is so I would believe it is a suction problem. I haven't verified with another gauge but it acts normal once pressure is achieved. Cold starts (<30 deg F) it can take up to 10 seconds to build pressure. Also can see a slight fluctuation (~2psi) at idle. It has the correct oil in it (5w-30). And have changed it once since noticing but problem persisted. I changed the oil pan ~9 months ago and changed the take up o- ring at that time. Once complete oil pressure was perfect 40psi at idle and up to 60psi under load. So I figured everything was gravy. Maybe I didn't quite torq the take up bolt enough and it has walked? If I don't hear back I'm gonna go ahead and change the oil pump and take up o-ring and keep my fingers crossed. Any help is appreciated! -Matt

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