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My dad always said oil was cheap insurance, so I've always changed every 2500 to 3000 miles. Now that I have the DMAX, many say that changing oil that often is a waste of oil. What makes diesel oil last so much longer? If I go to synthetic, and run the oil 8-9000 miles, should I change the filter in-between?Edited by: Roegs
 

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Quick and dirty answer, additives and the base oil stock. Ask this question over at BITOG and you'll get a more scientific explaination. Oil ain't what it used to be. Even in gas engines, it is foolish to change oil every 3K unless it is driven in severe service, such as very short trips all the time, where the engine does not come up to operating temperature.
 

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Plus there is more of it. 10 quarts instead of 4 or 5.
 

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You think 10,000 is a lot, my wifes Trailblazer with the 4.2 inline 6 says we can go up to 12,000. Of course I hit both around 5000, but with all these excellent reports of oil analysis' I'm rethinking to go even longer. At 30,000k and higher for price tag's these days, why continue to spend more on them if it truly isn't necessary?
 

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More oil, better filtering and cooling. Also most of the Duramax's if broken in properly have less blow by carrying combustion waste into the oil.It is a waste to change oil every 3K except for the first couple changes. I'm going to change mine every 5K becuse most of my driving is short trips of 10-25 miles around town. I f I were using it for mostly long hauls, light loads I'd probaly go to 10K.
 

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It's all about the oil quality today .... Today's standards and with environmentalist pressure the oil companies have developed excellent products ....
Duramax also has added capacity as noted ....
One thing you should keep in mind is that's based on staying with the stock power ....
If you should turn up the volume, you should adjust maintenance accordingly ....

Mac
 

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I ALWAYS CHANGE MY OIL AT 3000 MILES. I AGREE WITH YOUR DAD.


I DONT KNOW ABOUT YOU BUT THE OIL IS BLACK AT 3000. I USE ROTELLA T 15-40 MY TRUCK SEEMS HAPPY HERE IN ARIZONA AT THAT INTERVAL.
 

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FWIW, here's a picture of the oil with 5k on it from my 03 Dmax.


The oil on the dip stick at 3k also looks very clean.


Oil is Shell Rotella 5w40 Group-III "synthetic" and I also have an OilGuard Bypass. It's my understanding that one of the reasons the Dmax oil runs so clean compared to other Diesels is the efficiency of the combustion that results form the Bosch common rail system. A more complete burn results in less soot.


 

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I would like to add something to this discussion if I may
,


I use the hours meter as more of a gauge than the miles driven.


I tend to stay at around 100 hours on the oil before I change it out. Sometimes it is at 3K miles , other times it is a little longer.


I also use the weather as a variable too. During the winter months I tend to change it out sooner ( miles wise ) than the summer due to more idling time.


It's just something to think about.





T
NYEdited by: GMC-2002-Dmax
 

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Wow, my oil is very sooty after 3,000 miles. I change at 5,000.
 

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I change my oil filter at 3-4,000 and then drain the oil at 8,000. No problems so far. The oil may trap soot, but the filter is still the key, just like in fuel.
 

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STUPID QUESTION WHERE EXACTLY IS THE FULL MARK ON THIS STICK AND WHERE IS 1QT LOW??PICT FROM "JBPLOCK"
Edited by: mpl897
 

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mpl897,


Good question... I always thought that full was when the "F" was covered
with oil as shown in my pic... Not sure about the 1 quart low... So far at
20kmiles my Dmax hasn't used any oil between changes (4-5kmi)..


Edited by: jbplock
 

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any answers?
 

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You may all find this hard to believe, but the COLOR OF THE OIL DOES NOT INDICATE IT"S CONDITION. (Unless it's got water in it, then it's obvious)The only true way to tell the condition of the oil is by a "Used Oil Analysis" or UOA as it is commonly refered to.


It would not hurt to do a UOA from time to time. This also detects fuel and water. Good ammunition if you suspect bad injectors or leaky return lines.


If you do a UOA on your dino oil at 5K you will be surprised at how much life is left.
 

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Good question, mpl897, my 2001 stick doesn't have the "F and A" on it. Looks like the "A" is to indicate "ADD". I've found that my notches are about 1 pint each. That would make it about 1-1/4 quarts between the top of the notch below "F" to the bottom of the notch above "A"
 

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Pick said:
... the COLOR OF THE OIL DOES NOT INDICATE IT"S CONDITION... The only true way to tell the condition of the oil is by a "Used Oil Analysis" or UOA...


If you do a UOA on your dino oil at 5K you will be surprised at how much life is left.
Pick,

Good point on UOA! I've been doing UOA on all my vehicles for several years. UOA identified a loose turbo resonator connection on my 98 6.5 - silicon was running at 45 ppm. I added a clamp and Si dropped on the next sample. Without doing the UOA I would never had known until it was too late. The point about oil color in the previous post was mainly to point out how clean the oil runs in the Duramax compared to other diesels like the 6.5. As you pointed out color alone is not the sole indicator of oil condition. My Dmax UOA's also have indicated considerable life left in the oil after 5kmi with TBN values as high as 9.5.


Idle_Chatter said:
… I've found that my notches are about 1 pint each. That would make it about 1-1/4 quarts between the top of the notch below "F" to the bottom of the notch above "A"
Tom,
Good info! Thanks!


Edited by: jbplock
 
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