Home » Public Forums » GMCnet » Which oil?
| Which oil? [message #147379] |
Sat, 22 October 2011 11:01  |
biggreen
Messages: 347
Registered: June 2011
Location: Northeast Florida
Karma: 1
|
Senior Member |
|
|
What is the present recommendation on motor oil. Manual shows straight 30 or 40 wt depending on climate, but I've seen others recommending synthetics.
Mine is a 77 403 w/ 54000 mi. In Florida.
Light usage.
Thanks.
|
|
|
|
|
|
| Re: Which oil? [message #147394 is a reply to message #147379] |
Sat, 22 October 2011 15:27  |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| biggreen wrote on Sat, 22 October 2011 12:01 |
What is the present recommendation on motor oil. Manual shows straight 30 or 40 wt depending on climate, but I've seen others recommending synthetics.
Mine is a 77 403 w/ 54000 mi. In Florida.
Light usage.
Thanks.
|
R.D.
It almost doesn't matter any more as long as you find something with adequate ZDDP or add some on your own if you believe it is required as even that is a subject of some controversy these days.
The reason for the straight weight call out is that at the time these engines were manufactured, multi-viscosity oil really sucked. (That is technical term used to describe poor performance.) They had just terrible "shear-down" and you would soon end up at the viscosity of the base stock > about 7 for a 10WXX. They do that don't anymore. Just because I'm a paranoid engine guy, I tend to stay with the high end. I know this may cost me some fuel rate, but I would prefer to buy fuel than an engine. I would not use a 5W-anything in a coach engine. A 10w30 or 40 will do just fine.
Some are of the opinion that the high level of anti-wear additive ZDDP is not required after the camshaft has gotten through break-in. I - personally - don't agree. But, you know how they compare opinions to other things.
Now you have to decide who you believe.
There are several companies that are marketing 15w40~50 advertised as being for older or high mileage vehicles. Read the labels and look for one with that says it is high zinc/ZDDP content. It will say all over the label "Not for vehicles equipped with a catalyst" or some such...
I currently have a three year (maybe more) stock of coach lube oil so I have not shopped for it recently. I really can't tell you what is on shelves. Me, I am running Mobil I 15W-50 (no longer available to me) with a MoS2 on top of that. As I said, I'm paranoid.
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
|
|
|
|
|
|
| Re: Which oil? [message #147409 is a reply to message #147379] |
Sat, 22 October 2011 18:32 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
|
Senior Member |
|
|
i've been running diesel oil but as i understand it has more detergent and that can cause problems. i've noticed that my oil turns black very soon after a change. i switched to some old oil i had on hand that rated CF. the oil stayed clear for much longer. my plan for the future is to use modern oil and add zinc additive. i'm in Matt's school.
Fred V
'77 Royale RB 455
P'cola, Fl
|
|
|
|
|
|
| Re: [GMCnet] Which oil? [message #147418 is a reply to message #147400] |
Sat, 22 October 2011 19:14 |
|
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| Robert Mueller wrote on Sat, 22 October 2011 18:05 |
Matt,
I'm in your club! Where do you get the MoS2?
Regards,
Rob M.
|
Rob,
I can only buy the stuff I like at a reasonable price by getting it from the manufacturer. Problem, they changed hands and now a minimum order it 500$. Last time I did this, my cost was about 23$us for the 1# bottle. That works out to be 20 some 1 pound bottles of 0.5m MoS2 - 30% by weight in 150ssu (~SAE 20) oil. That plus shipping is what I made it available to GMC owners for. I don't believe I have any unopened bottles at this time, and I probably won't order more for another year.
I don't know how an normal person would get this stuff. I can find similar on Ebay, but it is dear.
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
|
|
|
|
| Re: [GMCnet] Which oil? [message #147422 is a reply to message #147418] |
Sat, 22 October 2011 19:38 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Matt,
Thanks!
I did an eBay search for MoS2 and Molybdenum Disulfide and a few popped up. You're right, the prices are NUTS! As we say Downunder
"it's as dear as poison!"
The funny thing was that there was one guy offering it for Pinewood Derby Racer lubrication needs. So you can put in your GMC's
engine oil and on your Pinewood Derby Racers axles!
Regards,
Rob M.
-----Original Message-----
From: Matt Colie
Rob,
I can only buy the stuff I like at a reasonable price by getting it from the manufacturer. Problem, they changed hands and now a
minimum order it 500$. Last time I did this, my cost was about 23$us for the 1# bottle. That works out to be 20 some 1 pound
bottles of 0.5m MoS2 - 30% by weight in 150ssu (~SAE 20) oil. That plus shipping is what I made it available to GMC owners for. I
don't believe I have any unopened bottles at this time, and I probably won't order more for another year.
I don't know how an normal person would get this stuff. I can find similar on Ebay, but it is dear.
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
|
|
|
|
| Re: [GMCnet] Which oil? [message #147472 is a reply to message #147413] |
Sun, 23 October 2011 08:12 |
|
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| Robert Mueller wrote on Sat, 22 October 2011 19:41 |
Fred,
I was told that it was heat that turned the oil black many years ago, can anybody confirm that or is it an "old mechanics tale?"
Regards,
Rob M.
|
Rob (and everybody reading),
When lube oil goes black (dark) there can be a number of reasons, but there are two that are such serious leaders that the others don't matter.
- The most common reason lube oil goes dark is that the oil is collecting particulate that comes largely from combustion by-products. There may also be some material from wear points in the engine, but this source becomes very small after the initial run-in. This is the reason many manufactures specified non-detergent oils for so long. The detergent will keep this material from clumping and it will remain in suspension - making the oil dark - much longer. This is actually a good thing in that the particulate will not collect in places that interferes with other things.
- Heat alone can do this, but it is unlikely in an engine in normal passcar service. It is not even all that likely in a coach engine that is not seriously involved in mountaineering. There are only two places in an engine that are expected to be that hot ever; The underside of the piston crowns. They are intentionally oil cooled. (Many diesels actually have jets to spray lube oil there.) And, in coach engines or other old V engines, under the intake manifold where heat riser (cross-over) is located. This one is not planned and the turkey pan is the best that they could do to deal with it at that time. There should not be evidence of coking (cooked oil) any place else in the engine.
Regular (dino) oil has a temperature limit of 305°F. This is not even a time/temperature thing. If an oil molecule gets heated to 305°F, it comes apart and is no longer oil. This does add to the particulate in the oil.
Detergent oils were originally misunderstood by many. When an old engine was changed to a detergent oil, that oil would instantly go dark. This is not an issue, but it made people uncomfortable. Stories about this abound, but this is early Sunday morning in the north country and I have a coach to winterize today.
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
|
|
|
|
| Re: [GMCnet] Which oil? [message #147484 is a reply to message #147472] |
Sun, 23 October 2011 09:08 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Matt,
I should have qualified my statement by noting that I was told that heat changed oil black in the late 1960's by Frank Kozatska when
I worked part time in his Texaco station outside Westover AFB in Chicopee Falls, MA.
Regards,
Rob M.
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Matt Colie
Rob (and everybody reading),
When lube oil goes black (dark) there can be a number of reasons, but there are two that are such serious leaders that the others
don't matter.
- The most common reason lube oil goes dark is that the oil is collecting particulate that comes largely from combustion
by-products. There may also be some material from wear points in the engine, but this source becomes very small after the initial
run-in. This is the reason many manufactures specified non-detergent oils for so long. The detergent will keep this material from
clumping and it will remain in suspension - making the oil dark - much longer. This is actually a good thing in that the
particulate will not collect in places that interferes with other things.
- Heat alone can do this, but it is unlikely in an engine in normal passcar service. It is not even all that likely in a coach
engine that is not seriously involved in mountaineering. There are only two places in an engine that are expected to be that hot
ever; The underside of the piston crowns. They are intentionally oil cooled. (Many diesels actually have jets to spray lube oil
there.) And, in coach engines or other old V engines, under the intake manifold where heat riser (cross-over) is located. This one
is not planned and the turkey pan is the best that they could do to deal with it at that time. There should not be evidence of
coking (cooked oil) any place else in the engine.
Regular (dino) oil has a temperature limit of 305°F. This is not even a time/temperature thing. If an oil molecule gets heated to
305°F, it comes apart and is no longer oil. This does add to the particulate in the oil.
Detergent oils were originally misunderstood by many. When an old engine was changed to a detergent oil, that oil would instantly
go dark. This is not an issue, but it made people uncomfortable. Stories about this abound, but this is early Sunday morning in
the north country and I have a coach to winterize today.
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
|
|
|
|
| Re: [GMCnet] Which oil? [message #147498 is a reply to message #147472] |
Sun, 23 October 2011 10:28 |
 |
mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
|
Senior Member |
|
|
| Matt Colie wrote on Sun, 23 October 2011 06:12 |
...
- Heat alone can do this, but it is unlikely in an engine in normal passcar service. ...
...
Regular (dino) oil has a temperature limit of 305°F. This is not even a time/temperature thing. If an oil molecule gets heated to 305°F, it comes apart and is no longer oil. This does add to the particulate in the oil. ...
|
Pretty much explains why dino oil is 'OK' in the coach but a BAD thing for the wife's turbo charged Audi. The turbos cook the oil.
Synthetic only... to bad it leaks oil like an old Audi!
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
|
|
|
|
| Re: [GMCnet] Which oil? [message #147563 is a reply to message #147472] |
Sun, 23 October 2011 18:47 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Another to add - Ricardo chamber Diesels will turn oil to ink within a very few hours of operation. I'm told this is a result of lower combustion temps leading to more blowby, you might know the facts.
--johnny
________________________________
From: Matt Colie <matt7323tze@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Sunday, October 23, 2011 9:13 AM
Subject: Re: [GMCnet] Which oil?
Robert Mueller wrote on Sat, 22 October 2011 19:41
> Fred,
>
> I was told that it was heat that turned the oil black many years ago, can anybody confirm that or is it an "old mechanics tale?"
>
> Regards,
> Rob M.
Rob (and everybody reading),
When lube oil goes black (dark) there can be a number of reasons, but there are two that are such serious leaders that the others don't matter.
- The most common reason lube oil goes dark is that the oil is collecting particulate that comes largely from combustion by-products. There may also be some material from wear points in the engine, but this source becomes very small after the initial run-in. This is the reason many manufactures specified non-detergent oils for so long. The detergent will keep this material from clumping and it will remain in suspension - making the oil dark - much longer. This is actually a good thing in that the particulate will not collect in places that interferes with other things.
- Heat alone can do this, but it is unlikely in an engine in normal passcar service. It is not even all that likely in a coach engine that is not seriously involved in mountaineering. There are only two places in an engine that are expected to be that hot ever; The underside of the piston crowns. They are intentionally oil cooled. (Many diesels actually have jets to spray lube oil there.) And, in coach engines or other old V engines, under the intake manifold where heat riser (cross-over) is located. This one is not planned and the turkey pan is the best that they could do to deal with it at that time. There should not be evidence of coking (cooked oil) any place else in the engine.
Regular (dino) oil has a temperature limit of 305°F. This is not even a time/temperature thing. If an oil molecule gets heated to 305°F, it comes apart and is no longer oil. This does add to the particulate in the oil.
Detergent oils were originally misunderstood by many. When an old engine was changed to a detergent oil, that oil would instantly go dark. This is not an issue, but it made people uncomfortable. Stories about this abound, but this is early Sunday morning in the north country and I have a coach to winterize today.
Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
Goto Forum:
Current Time: Tue Oct 01 02:17:11 CDT 2024
Total time taken to generate the page: 0.01155 seconds
|
GMCforum
Search
Help
Register
Login
Home
