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Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. [message #336537 is a reply to message #336504]

Thu, 30 August 2018 14:41

BobDunahugh

Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA

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Senior Member

Owners get WAY to wrapped up in oil pressure readings. My race engines can run in the 7 to 8,000 RPM range at 25 PSI all day. 12.4 to 1 compression ratios. 110 octane leaded fuel. ( at 6.50 a gallon. Then just 3 miles to that gallon. And you thought our GMC's cost a lot per mile ) That's serious stress on parts. Our GMC's are at 8 to 1 as a reference . My race engine idle oil pressure can get down to 12 to 16 PSI. I want my HP/torque going to the wheels. Not going to the oil pump. So it can put higher dumb numbers on a gauge. As to your GMC. 10 psi at idle. 20 at speed are both at the low end. But fine. Then remember to avoid lugging. Put some 20/50 dino oil in. The oil is just a little thicker. Changer your oil/filter every 2,000 miles. Our engines were dirty engines when new. They need frequent oil/filter changes more the expensive oils. Bob Dunahugh

________________________________
From: Bob Dunahugh
Sent: Wednesday, August 29, 2018 12:40 PM
To: gmclist@list.gmcnet.org
Subject: RE:Tid Bits: Oil consumption. It's all in how/where it's consumed.

Sully. Don't know when most of the oil consumption would occur. Never even saw a hint of oil smoke ever. Thought that the 50 might help some. It did. Bob Dunahugh

________________________________
From: Bob Dunahugh
Sent: Monday, August 27, 2018 9:53 PM
To: gmclist@list.gmcnet.org
Subject: Tid Bits: Oil consumption. It's all in how/where it's consumed.

6 years ago. I knew someone that got very upset that their engine consumed one qt every 300 miles. So we looked at the spark plugs. All the spark plugs showed about the same as to discoloration/deposits. The compression test came in at reasonable numbers. At 115 to 123 psi. Not great. But not bad. Inspection camera showed oil washing around the edges of the pistons. All washing on all pistons was about the same width. Again. Not a great sign. But not bad. Just expected. Put a dial indicating micromotor to the top of each rocker arm. Just looking for consistency between all the intake. Then all the exhaust. Looked good. But that test doesn't show how much the lifters are dished. Or how much of the cam lobes are gone. Again used the inspection camera to check the cam gear/chain. Had been changed at some past point. Warm oil pressures were13psi at idle. 21psi at speed. This is a candidate for a high volume oil pump. But the pump could over load the piston oil control rings. That are already over loaded. Thus it could up oil consumption. I suggested running it as is. And run a heavier oil. He's been using 20W50 oil. Still running well. Oil consumption has been at about 400 miles per qt. If the engine had all the oil consumption issues in just one or two cylinders. That's time for a rebuild. As for what's best for you. Not my monkeys. Not my circus. Bob Dunahugh
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		[GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: BobDunahugh on Mon, 27 August 2018 21:53
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: jimk on Mon, 27 August 2018 22:43
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: sgltrac on Mon, 27 August 2018 23:10
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: BobDunahugh on Mon, 27 August 2018 23:09
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: BobDunahugh on Wed, 29 August 2018 12:40
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: James Hupy on Wed, 29 August 2018 13:22
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: GMC.LES on Wed, 29 August 2018 14:12
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: James Hupy on Wed, 29 August 2018 14:27
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: johnd01 on Wed, 29 August 2018 23:50
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: GMC.LES on Thu, 30 August 2018 07:37
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: Richard Denney on Thu, 30 August 2018 08:58
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: James Hupy on Thu, 30 August 2018 09:32
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: Mike Kelley on Thu, 30 August 2018 09:56
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: jimk on Thu, 30 August 2018 09:54
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: Matt Colie on Thu, 30 August 2018 12:29
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: James Hupy on Thu, 30 August 2018 13:03
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: k2gkk on Thu, 30 August 2018 21:06
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: James Hupy on Thu, 30 August 2018 21:19
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: BobDunahugh on Thu, 30 August 2018 14:41
		Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. By: JohnL455 on Thu, 30 August 2018 18:00

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