Oil Pressure Gauge

tmar480 · May 30, 2019

I have a 2018 GMC Sierra with 8,000 miles on it so far and I've noticed recently that my oil pressure gauge is being a little weird. I just got a oil change 2k miles ago and when I'm at idle at a stop light or whatever the pressure gauge drops down like 3 notches before its at 0 then as soon as I hit the gas it jumps back up to the normal line. I thought I was just low on oil and I put 2 quarts in which was a little more than I needed but I'm not worried about that for right now but it is still not at the normal line when at idle. So it can't be that I am low on oil. Is this something that is common with these trucks or is something wrong? I'm new to the whole GM truck thing so I'd thought I'd ask on here before I jump to conclusions. Please let me know if there is an easy fix or something!

Thanks guys!

txab · May 30, 2019

Your pump has variable output based on demand. It's not going to sit at a constant pressure. Make sure your engine oil level is at the full mark and not way above. Next time just check the oil level prior to dumping in two quarts. If it's full, more oil not going to help.

Edit: What pressure is it at? Your description of "3 notches"..... are you saying it's at about 10 psi, the first mark above zero. Or the the third mark which would be about 30 psi

tmar480 · May 30, 2019

18 minutes ago, txab said:

Your pump has variable output based on demand. It's not going to sit at a constant pressure. Make sure your engine oil level is at the full mark and not way above. Next time just check the oil level prior to dumping in two quarts. If it's full, more oil not going to help.

Edit: What pressure is it at? Your description of "3 notches"..... are you saying it's at about 10 psi, the first mark above zero. Or the the third mark which would be about 30 psi

Well I didn't add two quarts of oil just because my oil pressure gage wasn't level. I've been burning a stupid amount of oil recently cause I drive on the highway a lot to work plus with the AFM burns a lot of oil as well. I was below my lowest dot on my oil stick hence why I added two quarts.

Yeah Id say about 30 PSI maybe 25 depending on the day honestly.. After I added the oil it went up to around 40 but fluctuated when at idle.

CamGTP · May 30, 2019

Not sure what the recent spec is for these engines but it's likely to be around 10-12psi for every 1,000 rpm. So if you are at 25-30psi at 500-600rpm at idle with these new variable pumps, it's perfectly normal.

tmar480 · May 30, 2019

1 hour ago, CamGTP said:

Not sure what the recent spec is for these engines but it's likely to be around 10-12psi for every 1,000 rpm. So if you are at 25-30psi at 500-600rpm at idle with these new variable pumps, it's perfectly normal.

Alright, I just didn't know if it was normal for that oil pressure gauge to be fluctuating like that. Sound like its normal from your description and I shouldn't be worried.

txab · May 30, 2019

Based on your additional info, I'd say you're "normal", except for going through oil as you mention

tmar480 · May 30, 2019

2 minutes ago, txab said:

Based on your additional info, I'd say you're "normal", except for going through oil as you mention

Yeah I've been reading how much the AFM burns oil and I'm waiting to get the Range AFM Disabler soon. But I continue to check my oil every 1k just to make sure I'm in the clear. But I appreciate it.

JimCost2014 · May 30, 2019

8 minutes ago, tmar480 said:

Yeah I've been reading how much the AFM burns oil and I'm waiting to get the Range AFM Disabler soon. But I continue to check my oil every 1k just to make sure I'm in the clear. But I appreciate it.

1 quart every 1000 miles is kind of alarming.

I would have it the dealer having the engine checked out, AFM does not burn oil at that rate.

5.3 in our 16 Tahoe, 6.2 in my 18 Silverado, both "loose" .5 to a quart every 5000 miles.