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  1. #1

    Default got my first duramax diesel...what engine oil do you recommend...

    i have an 06 chevy silverado 2500HD LT3 4x4 6.6l LBZ diesel crew cab180,000 miles on it ....my first diesel....im not shure which oil would be best for my truck someone told me mobile Delvac 15W-40....has anyone used this on their truck...any other suggestions..thanx
    06 chevy silverado 4x4 duramax 6.6L 2500HD LT-Diesel

  2. #2
    Sr. Apprentice
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    Dec 2011
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    Default

    Several Two very different approaches taken by people. Many go with a synthetic and do frequent oil changes which is a complete waste of money though the oil companies love it. Second is to use a synthetic and use the computer to tell when to change the oil or send in samples periodically for testing at a lab. Third approach is to use a dino or conventional API level motor oil and change every 5k to 7.5K miles depending upon your type of driving.

    Hauling a heavy load most of the time or taking lots of short trips are going to require more frequent oil changes than if the truck is driven as a commute vehicle with average trips of 45 minutes or longer. I do half and half and so change at 5000 miles and use conventional API oil.

    You have a pre-DPF engine and can use (if you can find it) a CI-4 oil like Chevron Delo 400. The CI-J are what are used with an engine with a DPF to help manage the soot generated. A CJ-4 oil like the Chevron Delo 400 LE is not nearly as good and has an inferior additive mix for an engine such as yours. Valvoline Premium Blue (Cummins recommends this oil) used to come in a CI-4 formulation but now it shows as being CI-4/CJ-4 so who knows what the is in the new formulation.

    Additives are 25% of what goes into a gallon of oil and it is the additives that have the biggest impact on performance of the oil. There is very little difference between different API base stocks and that includes conventional versus synthetic motor oil base stocks. Shell Rotella T synthetic, Cummins Premium Blue conventional and synthetic versions, Pennzoil Long Life conventional, Chevron Delo 400, and Red Line Diesel synthetic. Costs range from $10 to $35 per gallon and unless you drive in freezing weather the 5W of the synthetics is not going to help engine performance or life.

    In terms of excellent CI-4 motor oils as analyzed by labs used by fleet operators there are

  3. #3

    Default

    When it comes to oil, I found there is some personal preference involved. And as elkhornsun stated, you will have to make the choice of synthetic vs conventional. Previous to getting my duramax, I had two different Powerstrokes, a '95 7.3L and a 2006 6.0L. For the 7.3L, I used Chevron Delo 400 and the truck ran great. When I replaced my 7.3L with the 6.0 (I needed a crewcab for my growing family and my 7.3L just didn't have enough room in the cab), I kept using Delo. When I took it into the local dealership for some routine service work, I was able to talk to the mechanic and he suggested that I stay away from Delo because the fuel injectors use the oil to operate, which requires the oil to operate at a very high pressure. Delo doesn't have a good additive package for high pressure systems and foams up due to the higher pressure. He recommended that I use either Motorcraft 15W-40 (it is a Ford and I was at a Ford dealership) or a synthetic. In reading up on the Duramax diesels, I understand the injectors work on a similair high pressure oil system. I did some of my own research on this topic in web searches and on Ford Forums and came to conclusion that what he stated was correct. The 6.0L also starts better in cold weather with a 5W instead of a 15W as elk stated so I switched to Shell Rotella. Based on this information, I would choose either a conventional oil with a good additive package for high pressure systems or a synthetic. Which conventionals have a good additive package for high pressure fuel injector systems? Unfortunently I don't know, but I do know that Delo 400 LE doesn't. Don't know if this helps, but thought I would throw out my experience based on a trustworthy mechanics recommendations. If your wondering, I am new to Dmax, but I plan to Shell Rotella. The nice thing about the Dmax is that it only takes 10 quarts with filter change, my 6.0 took 14 quarts and my 7.3 took 15 quarts.
    2008 C5500 Duramax Dutchmen Motorhome

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