Cummins 855 inframe

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by tendoy, Aug 27, 2025.

  1. tendoy

    tendoy Bobtail Member

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    Owner operator and my own mechanic. Just ran the overhead on my old big cam 3. She is running good and I put a ht60 on it. It is using some oil and I predict an inframe in the near future. Is this something I can do with a service manual and some mechanical knowledge? I’ve never been that deep in one. Anything to look out for?
     
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  3. tendoy

    tendoy Bobtail Member

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    Just wanted to add my engine is CPL 625
     
  4. Star Rider

    Star Rider Road Train Member

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    How much oil is it using? A gallon a day, a gallon a week?
    Only you know your abilities.
    If you mess it up can you afford to buy another complete engine?
     
  5. tendoy

    tendoy Bobtail Member

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    3/4 of a gallon a day. Definitely can’t afford to mess it up
     
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  6. Lazer

    Lazer Road Train Member

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    Without this degenerating into an ‘oil thread’, 3 quarts a day is borderline, not horrible, not terrible, but it’s enough. Just for curiosity, does consumption change if you use a different brand/grade of oil? Different weight change anything? Prolonged change intervals make any difference?
     
    Bean Jr. Thanks this.
  7. tendoy

    tendoy Bobtail Member

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    That’s a good question. This truck is mostly used seasonally for hay hauling and gravel. When I use it every day for a couple weeks the consumption starts to go down. It seems like the hardest thing on it is sitting for any prolonged periods. I haven’t tried a different oil, I just run fram 15/40 in it right now. Any suggestions on a different type to try?
     
  8. Lazer

    Lazer Road Train Member

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    Mobil, Chevron, Citgo, Mystic, Shell are all very good well known makers of 15w-40 diesel engine oil. Wheather you want to pony up the coin for synthetic, or synthetic blend, or even conventional is up to you. Any of those brands should be better performing that generic Fram.
     
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  9. Deere hunter

    Deere hunter Road Train Member

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    How many miles on this motor?
     
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  10. 062

    062 Road Train Member

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    What happens if you don’t top it off,continue to go down or level up?
     
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  11. Star Rider

    Star Rider Road Train Member

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    Yeah, try running it a gallon low, you might be surprised in a good way.
    Some of the old Cummins would use oil when topped off, run them a gallon low and then never use oil.
     
    Deere hunter, 062 and Diesel Dave Thank this.
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