8.1 idle oil pressure

yukon25008.1 · February 25, 2012

I had a post months ago about oil pressure but cant find it.

My issue is at idle with the motor up to temp my pressure is down around 10-12..

And its starting to concern me, Even 1/2 throttle it doesnt exceed 40, Im using mobil 1 5w/30 synthetic high mileage..its only got 110,121.. my 01 chevy van 5.7 with 190,000 has the sme oil and the pressure is near 60 at times Thanks for any advice

dewfpo · February 25, 2012

I have 22 psi (if you believe the oil pressure gauge) at hot idle with 5W40 oil and only 15,000 miles on the engine. 2,500 rpm & hot it's about 40-45 psi.

DEWFPO

markw8 · February 26, 2012

Sounds normal for the mileage. Newer engines don't usually carry as high of pressure as in the past. You have to consider 100k+ miles too.

Mark

yukon25008.1 · February 26, 2012

So why does the 5.7 with 190,000 have better pressure then the 8.1 with 110,000

Same oil..

markw8 · February 26, 2012

Try putting a good mechanical guage on both and see what you have.

Mark

yukon25008.1 · February 26, 2012

I was hoping the gauge was off, what else would cause low pressure besides wear/age

markw8 · February 27, 2012

The guage might be off. Have you actually tried a good mechanical guage? Also you need to compare it with another 8.1. Apples to apples.

Mark

yukon25008.1 · February 27, 2012

Thanks..I will, Any idea what it should be??

markw8 · February 28, 2012

Nope.

Mark

dewfpo · February 28, 2012

Thanks..I will, Any idea what it should be??

From what I've seen, the numbers I posted above seem to be normal for the 8.1L engine. I've heard the engine was designed with a high flow rate bias to the oil pump over high pressure. This is better for big, torquey, hard-working, lumbering engines.

DEWFPO

yukon25008.1 · February 29, 2012

What makes you run 5w40 vs 5w30

dewfpo · February 29, 2012

I felt I was going thru the M1 5W30 faster on this 8.1L engine than any other engine I've used it in. It only took once for the "low engine oil" warning light to catch me by surprise for me to try the 5W40 I had sitting in the garage (I use it in other engines that call for it). I tried it and my oil consumption rate went down and the engine is very quiet so I've been using it since my second change out. I drive in weather that ranges from -20F to +105F so I have no worries. The engine seems happy with it and so am I.

DEWFPO

yukon25008.1 · February 29, 2012

Sounds good... If you had to do the 2nd battery again would you??

I was thinking about it, I just swapped the bad 105 with a delphi 145 amp alternator

dewfpo · February 29, 2012

Sounds good... If you had to do the 2nd battery again would you?? I was thinking about it, I just swapped the bad 105 with a delphi 145 amp alternator

No, I wouldn't go for the second battery again. I have the TP2 option (isolated aux. battery).

My truck sits for 4-7 weeks at a time without being used and we have very cold temps occasionally in the winter so I was originally planning on hooking it up so that both batteries would be used to start the truck but I never got around to it. Turns out I never needed to. Even with the original batteries (11/2004 build date) the engine still starts on the first crank no matter how long it sits or how cold it is. I know they are living on borrowed time, but now I will have replace both batteries when I really only needed one.

DEWFPO