Would thicker oil in a high mileage GM 3.6L V6 help raise idle oil pressure?

[atikovi]

Recently got this car which has 140,000 miles and will be doing an oil change soon after running 1000 miles with a pint of Kreen in 10W30. The OP gauge is usually down to one or two bars at warm idle. Yesterday while stuck in bumper to bumper traffic for a half hour it would drop to no bars. (coolant temp is at 3/8) I didn't get any warning messages so assume it was OK. Is it? Gauge goes to 3 by 2000 rpm or so, and on cold starts it's at 3/4 so I think the sender is good. Thinking of going to 10W40 or 10W50.

 

[redhat]

I am guessing 10, 30 and then 50 psi? I wonder if this vintage GM is suffering from a similar issue some of the Gen III V8 LS engines did. Worn out oil pickup tube o-ring?

 

[Big_3_Only]

Originally Posted by atikovi

Recently got this car which has 140,000 miles and will be doing an oil change soon after running 1000 miles with a pint of Kreen in 10W30. The OP gauge is usually down to one or two bars at warm idle. Yesterday while stuck in bumper to bumper traffic for a half hour it would drop to no bars. (coolant temp is at 3/8) I didn't get any warning messages so assume it was OK. Is it? Gauge goes to 3 by 2000 rpm or so, and on cold starts it's at 3/4 so I think the sender is good. Thinking of going to 10W40 or 10W50.

I never had luck doing that. I actually tried using a 20w50 and I didn't see much improvement in pressure, if any. I kept being told that I needed very little OP at idle. But it was nerve racking to say the least.

 

[atikovi]

Originally Posted by redhat

I am guessing 10, 30 and then 50 psi? I wonder if this vintage GM is suffering from a similar issue some of the Gen III V8 LS engines did. Worn out oil pickup tube o-ring?

I can't say the numbers correlate to actual pressures, if so they would have put 10, 30 and 50 on the gauge.

 

[WyrTwister]

Get rid of the Kleen and put dome Dexos specification oil in it , of the proper viscosity . See what that does . How much money do you have in it ? What model year ?

 

[pitzel]

Why do you feel that you 'need' additional oil pressure? What do you think you'll accomplish with higher oil pressure? Low oil pressure isn't a bad thing if the oil itself is present and is being pumped. Oil pressure itself does not have any impact on the mechanical components of the engine -- only the proper presence of lubricant relative to the operating conditions does. You could put tar sludge into your engine and get very high oil pressure, but I think we'd all agree that such would not constitute a good lubricant.

 

[atikovi]

It's a 2009 so pre Dexos. And after 1000 miles the Kreen is pretty much gone anyway. It's calls for 5W30 so that would be a step back.

 

[atikovi]

Originally Posted by pitzel

Why do you feel that you 'need' additional oil pressure? What do you think you'll accomplish with higher oil pressure?

I don't like seeing the gauge go to nothing at idle.

 

[skyactiv]

Trust me when I say this, avoid using a thicker oil and don't pay attention to that worthless oil pressure gauge. Going from a 5Wwhatever to a 10 or 20W whatever will only cause more cold engine start wear. It is especially dumb to use a thicker oil when it's cold on an OHC engine design.

 

[atikovi]

Originally Posted by skyactiv

Trust me when I say this, avoid using a thicker oil and don't pay attention to that worthless oil pressure gauge. Going from a 5Wwhatever to a 10 or 20W whatever will only cause more cold engine start wear. It is especially dumb to use a thicker oil when it's cold on an OHC engine design.

The first number is the cold starting property of the oil. Wouldn't change that, just increase the warm rating. from 10W30 to 10W40 or 10W50. I don't expect starting below mid teens anyway. Suppose I could find 5W50 if necessary.

 

[Langanobob]

I think if it was my car and I was concerned about the idle oil pressure I'd install a quality aftermarket oil pressure gauge with real numbers on it.

 

[SwampSurvivor]

So with some quick googling, it looks like 10-15 PSI at hot idle is normal for these engines? This is the "high feature" v6, right? The camchain eater?

 

[atikovi]

Yup, replaced the chains a month ago.

 

[redhat]

Originally Posted by atikovi

Originally Posted by redhat

I am guessing 10, 30 and then 50 psi? I wonder if this vintage GM is suffering from a similar issue some of the Gen III V8 LS engines did. Worn out oil pickup tube o-ring?

I can't say the numbers correlate to actual pressures, if so they would have put 10, 30 and 50 on the gauge.

I would assume they do. I doubt it'd be measuring bar. If it IS psi, you easily could have 15-18psi of oil pressure there at hot idle which would be right inline with what Miller found online. If there's no strange engine noise, perhaps you're fire.

 

[atikovi]

Originally Posted by redhat

Originally Posted by atikovi

Originally Posted by redhat

I am guessing 10, 30 and then 50 psi? I wonder if this vintage GM is suffering from a similar issue some of the Gen III V8 LS engines did. Worn out oil pickup tube o-ring?

I can't say the numbers correlate to actual pressures, if so they would have put 10, 30 and 50 on the gauge.

I would assume they do. I doubt it'd be measuring bar. If it IS psi, you easily could have 15-18psi of oil pressure there at hot idle which would be right inline with what Miller found online. If there's no strange engine noise, perhaps you're fire.

Yes I understand that, and the info display would post a warning of low pressure if it was serious. Plus throw a code. Just don't like seeing nothing on the gauge.

 

[benjy]

idiot lights are not so great for sure, get a proper gauge or have an reliable independent check it, then go from there.

 

[ls1mike]

Got a proper gage, check it. I could be as simple as the oil pressure sending unit.

 

[ragtoplvr]

Once we were rebuilding a 283 for a little S10, keeping the stock rear end and transmission. It came out of a grain truck, ran hard all of it's little life. Bored it 60, new pistons had rod big end resize. The crank was perfect so chamfer and polish. New oil pump. Start it up, 5 psi at idle, 15 at 3000. Pull it out, take it apart. Plastigauge all bearings, get new oil pump. still 5 psi at idle, 20 at 3000. Out it comes again. Pull oil galley plugs and look in there hey, why is there light shining ½ way down. Block casting flaw, the cast iron never fully flowed around it or core shifted or ???. This motor NEVER had more than probably 20 PSI in it's entire life. In a grain truck, ½ of the miles was 40 MPH wide open axle in low. And the crank was great. It don't take much oil pressure I guess. Splash lube is better than you think. Well getting, cleaning and machine on another block did hurt the budget. Oil light never came on in truck. And the lifters were quiet too. It really doesn't not take much oil pressure.

 

[Win]

So, you have a 2008 G8, the only year that had the voltmeter and oil pressure gauges installed, and the oil pressure is indeed being displayed in metric Bar units; my rule of thumb is 1 bar = 15 psi ... Having had one of these cars since brand spanking new, with a Fisherman's Bend HF V6 installed, your pic of the idle oil pressure looks completely normal to me; you should see 1 to 1.5 bar at idle increasing to 3 to 3.5 bar at normal operating RPM. I have not seen my idle pressure drop below 1 Bar, but if you go with a thicker oil, I probably would not go more than 0-40, or 5-40. I wouldn't worry much about it, to tell you the truth. The low oil pressure is probably some energy saving thing, wait until you see the alternator go into energy saving mode ... BTW, if you want to go into the engineering menu on the car, depress and hold the left side roller rocker before starting the car, and then release it after the car starts. This will provide you some additional data on the vehicle's operating points.

 

[atikovi]

Originally Posted by Win

your pic of the idle oil pressure looks completely normal to me; you should see 1 to 1.5 bar at idle increasing to 3 to 3.5 bar at normal operating RPM.

That's how it looks right after it's warmed up. After coming off the highway it will have 1 bar. If there is lots of stop and go traffic like the last traffic jam, it shows no bars. Will try the 5-40 just to see what it does.