Home » Public Forums » GMCnet » Oil change frequency (Edmunds article)
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| Re: [GMCnet] Oil change frequency [message #193999 is a reply to message #193982] |
Tue, 25 December 2012 21:01   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Robert Mueller wrote on Tue, 25 December 2012 18:25 |
Rick,
Good find, interesting article and videos.
<snip>
Double Trouble consumes about a quart of oil every 400 miles.
<snip>
Question:
1 - How does adding one quart every 400 miles effect the oil?
2 - Do the contaminants build up or get reduced?
Regards,
Rob M.
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Rob,
You do (among a few others) have a knack for opening questions that need very complex and involved answers to fairly answer the question.
Answer 1 - Probably not (see answer 2)
Answer 2 - Yes
Explanations: There are two common modes of lube oil consumption.
First is ingestion. This is when lubricating oil is consumed by either being carried over with the blow-by through the crankcase ventilation system, leaking down the guides or leaking into the charge air system by some other path. In these cases, the lube oil is consumed as a lot and typically that means additives, and contaminants as well. It had been conjectured that an engine that consumes a quart of lube oil every 4~500 miles is operating in a mode of continues lube oil replacement. As this is much like the lube oil consumption of a charge lubricated two stroke engine, the assumption would be that oil changes could be ignored, but this has other issues. More on this later.
Second is power cylinder lube oil consumption. In this case something is amiss with the lubricating oil control in the piston and cylinder. There can be many causes, and this being Christmas night, I will not cover too many. The two most common are cylinder surface (hone) issues that hold more lube oil that is required, and the other is piston oil control ring issues. Either of these can result in higher than expected lube oil consumption. Because the mode of consumption here is very specific, it may essentially control the oil consumption so it includes a minimum of both contaminants (such as carbon particulate and microscopic metals) and in this case, the majority of the undesirable material remains behind.
More confusion: In the first case, even though the lube oil is being consumed in bulk, some of the heavier contaminants may remain in the lube oil sump (pan).
To wit, it would be well advised to drain the lube oil on a periodic basis. If it were my engine to maintain, I would watch the fuel consumption and consider replacing the lube oil at intervals based on calendar and fuel consumption. I have never had to do this on an over the road vehicle so I can only guess that I would shoot for something that equated to approximately 100 hours at a typical road load.
Problem: If the lube oil consumption is caused by a high blow-by condition, then contaminants will be collected by the lube oil at a higher rate. So, if the lube oil consumption seems to be closely tied to fuel consumption, this is probably the case. But, without a handy lab guy to run analysis regularly, there is just no way to know.
I hope this helped someone out there in TZE land....
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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| Re: [GMCnet] Oil change frequency [message #194002 is a reply to message #193999] |
Tue, 25 December 2012 21:26 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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My take on lube oil service.....
Most of you will not know that the Detroit OEs do not do 3k lube oil service on durability evaluation test vehicles (also used for emissions compliance validation). The typical published lube oil service is in the 5k~7.5k mile or on an annual basis. So, those test vehicles are getting a lube oil service at twice the recommended interval or 15K miles of durability. They never get near a year.
Do they have lube oil quality related failures?
In a decade of monitoring durability engines, I never saw one.
I did see them in warranty, but you would never believe some of the things I saw come into warranty.
What do I do?
I do lube oil service on my vehicle as roughly 3K mile or annual (in the case of the Geo and the coach).
Why?
Because sometimes life gets more interesting that a guy can handle all at once. (Did you ever hear that the Chinese say "May you live in interesting times"? It is a curse.) In my own shop and with my own labor, it is just too inexpensive to pass up. That way when one of the regular use vehicles comes up for a service and the other is down for some reason so the service bay is tied up for longer than normal, (or some diligent fool has the bay filled up with old motorhome because his fuel line project is taking way longer than expected) the service requirement does not go critical. As I said above, in my case, it is just too cheap to pass it up.
Knowing this, I hope you can now make an informed decision as to what best fits your situation.
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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| Re: [GMCnet] Oil change frequency [message #194004 is a reply to message #193999] |
Tue, 25 December 2012 21:30 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Matt,
THANKS!
I hope that the questions I (among a few others) raise are better than the hackneyed subjects we've covered over and over and over.
I consider your statement a compliment, I'm making you (and others) use their grey matter! ;-)
Regards,
Rob M.
PS - Having reached the "somewhat" ripe old age of 66 I don't need or expect INSTANT answers; especially when I'm not paying for
them!
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Matt Colie
Rob,
You do (among a few others) have a knack for opening questions that need very complex and involved answers to fairly answer the
question.
Answer 1 - Probably not (see answer 2)
Answer 2 - Yes
Explanations: There are two common modes of lube oil consumption.
First is ingestion. This is when lubricating oil is consumed by either being carried over with the blow-by through the crankcase
ventilation system, leaking down the guides or leaking into the charge air system by some other path. In these cases, the lube oil
is consumed as a lot and typically that means additives, and contaminants as well. It had been conjectured that an engine that
consumes a quart of lube oil every 4~500 miles is operating in a mode of continues lube oil replacement. As this is much like the
lube oil consumption of a charge lubricated two stroke engine, the assumption would be that oil changes could be ignored, but this
has other issues. More on this later.
Second is power cylinder lube oil consumption. In this case something is amiss with the lubricating oil control in the piston and
cylinder. There can be many causes, and this being Christmas night, I will not cover too many. The two most common are cylinder
surface (hone) issues that hold more lube oil that is required, and the other is piston oil control ring issues. Either of these
can result in higher than expected lube oil consumption. Because the mode of consumption here is very specific, it may essentially
control the oil consumption so it includes a minimum of both contaminants (such as carbon particulate and microscopic metals) and in
this case, the majority of the undesirable material remains behind.
More confusion: In the first case, even though the lube oil is being consumed in bulk, some of the heavier contaminants may remain
in the lube oil sump (pan).
To wit, it would be well advised to drain the lube oil on a periodic basis. If it were my engine to maintain, I would watch the
fuel consumption and consider replacing the lube oil at intervals based on calendar and fuel consumption. I have never had to do
this on an over the road vehicle so I can only guess that I would shoot for something that equated to approximately 100 hours at a
typical road load.
Problem: If the lube oil consumption is caused by a high blow-by condition, then contaminants will be collected by the lube oil at
a higher rate. So, if the lube oil consumption seems to be closely tied to fuel consumption, this is probably the case. But,
without a handy lab guy to run analysis regularly, there is just no way to know.
I hope this helped someone out there in TZE land....
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Oil change frequency [message #194011 is a reply to message #194002] |
Tue, 25 December 2012 22:38 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Matt,
What you've noted in this and the preceding message has confirmed that changing the oil in Double Trouble once a year is fine.
Regards,
Rob M.
-----Original Message-----
From: Matt Colie
My take on lube oil service.....
Most of you will not know that the Detroit OEs do not do 3k lube oil service on durability evaluation test vehicles (also used for
emissions compliance validation). The typical published lube oil service is in the 5k~7.5k mile or on an annual basis. So, those
test vehicles are getting a lube oil service at twice the recommended interval or 15K miles of durability. They never get near a
year.
Do they have lube oil quality related failures?
In a decade of monitoring durability engines, I never saw one.
I did see them in warranty, but you would never believe some of the things I saw come into warranty.
What do I do?
I do lube oil service on my vehicle as roughly 3K mile or annual (in the case of the Geo and the coach).
Why?
Because sometimes life gets more interesting that a guy can handle all at once. (Did you ever hear that the Chinese say "May you
live in interesting times"? It is a curse.) In my own shop and with my own labor, it is just too inexpensive to pass up. That way
when one of the regular use vehicles comes up for a service and the other is down for some reason so the service bay is tied up for
longer than normal, (or some diligent fool has the bay filled up with old motorhome because his fuel line project is taking way
longer than expected) the service requirement does not go critical. As I said above, in my case, it is just too cheap to pass it
up.
Knowing this, I hope you can now make an informed decision as to what best fits your situation.
Matt
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Oil change frequency [message #194081 is a reply to message #193961] |
Wed, 26 December 2012 20:38 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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It's not worth the few dollars to try to stretch the envelope on how long I can go on the same dirty oil. To me it's it terms of fuel burn pounds about 3 x worse than in a car so 2K miles is 6K miles equiv. I change mine about every 2K or yearly. My friend at work was bragging about going 7500 miles on his 318 Durango between changes. I told him in the winter that's not smart and those motors had sludging issues. Soon he was shopping for new SUVs and had the Durango towed away with a nice rod knock.
John Lebetski
Woodstock, IL
77 Eleganza II
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