| [GMCnet] Dip stick calibration question [message #271502] |
Mon, 09 February 2015 11:53  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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One final thought on this subject.
I struggle to think GM would have kept the same oil refill specification throughout the entire 10 year run of the 455 production if it truly is wrong. It seems they would have seen warrantee repair issues from oil foaming or low oil pressure if the 6q at drain and fill with a filter was really over filling the engine at the normal low rpm ranges those engines saw in cars, Toros, or our MHs. And, if warrantee experience loss rates showed such a problem it stands to reason GM would have changed that spec somewhere along the line. They did not.
I am wondering if our conventional wisdom of adding back just 5q with a filter change is not overly influenced by what has been posted on the internet over the years by people using these engines in HP cars, jet boats and industrial applications where they are more likely to see higher RPM ranges more frequently and for longer periods of time.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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| Re: [GMCnet] Dip stick calibration question [message #271518 is a reply to message #271502] |
Mon, 09 February 2015 15:32  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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glwgmc wrote on Mon, 09 February 2015 12:53One final thought on this subject.
I struggle to think GM would have kept the same oil refill specification throughout the entire 10 year run of the 455 production if it truly is wrong. It seems they would have seen warrantee repair issues from oil foaming or low oil pressure if the 6q at drain and fill with a filter was really over filling the engine at the normal low rpm ranges those engines saw in cars, Toros, or our MHs. And, if warrantee experience loss rates showed such a problem it stands to reason GM would have changed that spec somewhere along the line. They did not.
I am wondering if our conventional wisdom of adding back just 5q with a filter change is not overly influenced by what has been posted on the internet over the years by people using these engines in HP cars, jet boats and industrial applications where they are more likely to see higher RPM ranges more frequently and for longer periods of time.
Jerry
Jerry,
You don't know the auto industry.
First, nothing gets changed unless it absolutely has to be changed. Usually this is when tooling is worn out.
As I noted in a prior post, some tech writer wrote the service book. He probably went to someone in the engine group and asked what the oil capacity of an Olds big block is as was told - Six. He put that in the book. Nobody has changed it. If you change something and something happens (even if it isn't actually related), it is your ass they come after. So, like the old Fords. For years many manuals specified 6°BTDC for base timing. You could set it that way and it would run. It would have haywagon performance, but it wouldn't blow up. When you finally played with those engines, you find that they wanted 12~14°. Whoa Nelli!!
Now, Why would the passcar application not have the same lube oil issues we have?
Simple Big Reason.
Cylinder pressure.
If you ran a passcar with the MAP (Manifold Absolute Pressure = inverse of vacuum) and therefore cylinder pressure we do, you would soon be in jail somewhere. That cylinder pressure means more blow-by. That higher air flow through the crankcase will pick up more of the lube oil that is being flung around by the crank shaft. So, a passcar gets better ring lubrication, but in a higher load application that flow will carry away more of the lube oil spray. This is also why the coach version has different valve gear covers.
I hope I didn't loose you along the way.
If I did and you are not so lost you can't frame a question, come back with what ever question you have and I will try again.
If you can't even assemble a question, tell me that too. I know I am much closer to this than normal people.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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