GM 6.0 normal idle oil pressure

[milkman636]

I'm looking at buying a used 2012 extended 3500 van with a 6.0 v8. With a warm engine at idle the oil pressure seems a little lower than I remember from my 98 pickup with old vortec engine. Even at highway speed it was noticeably lower.

The van is like new and only has 20,000 miles on it, so what I'm seeing may be perfectly normal for these engines, but I don't know. So I thought that I would reach out here for some input from some of you that have experience with these motors.

What kind of oil pressure readings do you normally see when you're idling? and when you're just cruising at highway speed?

 

[94BULLITT]

Are you looking at a electric gauge? They are not the most accurate, you really need to check the oil pressure with a mechanical gauge.

 

[milkman636]

Just looking at the standard gauge in the dash. I drove a personal GMC pickup from 97-02 and a few different GM work vans and trucks during that time and they all seemed to run similar oil pressures on the dash. So I just was looking for some feedback on where guys were seeing their pressure run on the current engines.

If a few guys on here were to chime in with similar readings to what I saw from this van I would just presume things were okay and buy it. Everything but the oil pressure reading on the van is near flawless. The numbers aren't terribly low, just noticeably lower than what I remember from my prior GM truck and van experiences.

If no replies come in, I might try to swing by a Chevy dealer tomorrow and take a couple new trucks for a test run just to where they run. I don't want to over-analyze this, but I won't feel good about ignoring it either.

 

[milkman636]

Took a brand new 3500 with a 6.0 for a good test drive this morning to answer my question. At a warm idle after running on the freeway the oil pressure would settle in just above 25 pounds. At 70 mph in OD it was turning between 1700 and 1800 on the tach and oil pressure was right around the 40 mark. The highest readings I saw were up near 50. The used one I looked at ran right in the same range. So it looks like these motors run about 10 psi lower on the gauge than I remember from my older GMC trucks and vans.

So after calling back the salesman on the used van and hitting him up for a few more bucks, we reached an agreement and I'm taking delivery tomorrow afternoon.

FWIW I read some internet chatter that talked about GM lowering oil pressures to reduce oil consumption in certain engines that have active fuel management. I have no idea if there is any truth to those statements, but found them interesting after reading some prior threads on here that referenced GM trucks using oil. I wonder if there is any truth to this ?

 

[EarPlug]

I had a 2001 Silverado 6.0 and from new to 140,000 miles it used 1 quart of Mobil 1 every 3000 miles. Then at 140k the oil consumption doubled to 2 quarts every 3000 miles. No burning or leaks. Dealer said it could cost up to $1000 just to diagnose the problem. I got rid of it.

 

[buickanddeere]

I installed oversize filters on my vehicles. Some cross referencing through the catalog will find a filter otherwise identical to the factory filter BUT longer.
iirc a Wix 51045 fits on the 6.0L . Wix 51036 on the V6 4.3 Vortec.

Engine oil gallery pressure is now higher at all times.

 

[JakeBrake]

My 2001 Buick Lesabre with 226,000 miles says that that my oil pressure is 131 lbs. It also says that this is normal. This is a digital gauge. The previous time the oil sending unit failed, the oil pressure reading dropped to "0 lbs.". Red warning lights and bells activated. I guess the lights and bells don't work for high pressure indications. Apparently, some GM sending units are not very reliable.

My 1995 GMC K1500 has a 5.7L engine with 192,000 miles. When the engine is cold, the oil pressure is about 50 lbs. Warm it's between 40 and 50 lbs. This is an analog gauge. Gauge maximum is 80 lbs. RPM's don't seem to affect the oil pressure very much.

I use conventional 10W-30 oil (whatever brand is on sale) in both vehicles. I change oil every 3,000 miles and I don't have to add oil between oil changes.

 

[milkman636]

My 2001 Buick Lesabre with 226,000 miles says that that my oil pressure is 131 lbs. It also says that this is normal. This is a digital gauge. The previous time the oil sending unit failed, the oil pressure reading dropped to "0 lbs.". Red warning lights and bells activated. I guess the lights and bells don't work for high pressure indications. Apparently, some GM sending units are not very reliable.

My 1995 GMC K1500 has a 5.7L engine with 192,000 miles. When the engine is cold, the oil pressure is about 50 lbs. Warm it's between 40 and 50 lbs. This is an analog gauge. Gauge maximum is 80 lbs. RPM's don't seem to affect the oil pressure very much.

I use conventional 10W-30 oil (whatever brand is on sale) in both vehicles. I change oil every 3,000 miles and I don't have to add oil between oil changes.

The pressure you list for your truck were more in line with what I was expecting to see. My '98 1500 ran 40 psi at warm idle from the day I bought to the day I sold it with around 100k on it. It would run up to 60 or so at the high end. After driving Fords for the last eleven years it is nice to actually see a gauge that will show some fluctuation in oil pressure with engine speed. Ford seems to prefer two position needles instead.

 

[milkman636]

I had a 2001 Silverado 6.0 and from new to 140,000 miles it used 1 quart of Mobil 1 every 3000 miles. Then at 140k the oil consumption doubled to 2 quarts every 3000 miles. No burning or leaks. Dealer said it could cost up to $1000 just to diagnose the problem. I got rid of it.

Stories like this make me think I'm taking a little bit of a gamble going back into a GM product.

It is strange that a motor can lose oil without leaking or burning it. It's got to go somewhere??? Makes me think that a couple of my kids may have futures as powertrain engineers at GM.:laughing:

Seriously though, with my needs the GM van is really the only vehicle that will meet them. It'll haul my family that is soon hitting 10, tow up to 10,000 lbs., and fit in my garage. Nothing else on the market can do all of those things for me. So even if it is a gamble, GM is the only game I can to bet right now.


Ford does offer a longer van too. But with their design I'd need to opt for the v10 to legally tow over 6500 lbs., and looking at seat placement I could have the weight of seven kids and up to 1000 lbs. of tongue weight all loaded behind the back axle. I just don't feel that good about the v10 mileage or the vehicle weight distribution inherent to their more axle-forward design.

 

[EarPlug]

Milkman - Mine was a 2001 and you're looking at a 2012. I would hope they have improved it in that time. Other than oil consumption it was a great motor and a great truck. Much better than the 2010 Silverado it traded for.