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15w-40 vs 30w vs 40wt

Discussion in 'Lubrication' started by Brandt, Aug 10, 2022.

  1. Brandt

    Brandt Well-Known Member

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    I did a search and it said that my criteria was too broad. So, I'm asking a question that has probably been answered 1000 times. These are the engines and what I am running in them. I run the a good number in the winter too for snow removal.

    90's Cat 3204 = 15w-40 Synthetic winter/summer
    80's Case 504 = 15w-40 syn winter/summer
    90's Kubota naturally aspirated = 15-40 syn winter/summer
    60's Cat D 330 Turbo = 15w-40 syn winter/ summer
    4-53 = 40w
    4-71 = 40 wt winter/summer

    I plan on replacing the 4-53 with a 4-53T. Should I continue to run 40w or a multi grade synthetic??
     
  2. crane operator

    crane operator Senior Member

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    At the age of your engines, I wouldn't bother with running synthetic, I think its a waste of $$$. They were all designed to run on dino oil, so that's what I use. If you don't care about the extra cost, the synthetic doesn't hurt.

    If you are running in bitter cold in the winter, the 40 wt. gets a little thick in the detroits. It just makes them slow turning over, and has a hard time pumping it around until the engine warms up. But I don't know what you're doing with them, if they have block heater or are in a heated shed, the 40 wt. isn't a problem.
     
  3. Brandt

    Brandt Well-Known Member

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    The 4-71 is in a grader. It is usually my last choice for snow removal, but if nothing else starts, it gets the nod. No heated shed, yes, block heater if it is close to power.
    You are probably right about the D 330 and Case 504 running dino oil. The 3204 has low hours and I feel there is a lot of life left in it.
    The 4-53 only gets started in the winter if I have to move it out of the way.
     
  4. John C.

    John C. Senior Member

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    As far as I know, Detroit always specified 40Wt for engine oil.

    Lately synthetic oils are in the auto parts stores are running less money in the five quart jugs than no synth oils.

    Just what is the difference anyway?
     
  5. Brandt

    Brandt Well-Known Member

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    I'm not a petrol engineer, but the best way it was described to me is: dino oil molecular structure is - open a box of uncooked spaghetti and toss it in the air. The way they land is dino oil. Synthetic oil molecular structure is the same spaghetti in the box.
     
  6. Birken Vogt

    Birken Vogt Charter Member

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    It's not so much the 40 viscosity of the Detroit oil, it is the sulfated ash content. Delo 100 is the specific type of oil for them, it is different than Delo 400.

    This may not even be valid any more with modern LE Delo oil, it might be OK to run 15W-40 in Detroits now, but nobody has any real data to back it up because Detroits are not important enough to do a bunch of tests on any more.

    I know the manuals specified weights less than 40 for cold temperatures, but I never paid attention because here in Ca it does not get that cold.

    I would run Delo 100 straight 40 and preheat the engine somehow if used in the cold wintertime.
     
  7. John C.

    John C. Senior Member

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    Here are a couple of videos put produced by Gale Banks.



    Personally I believe the term is used for marketing and justification to charge higher prices. The early marketing said you could run synthetics much longer than conventional oils. I had clients using oil analysis programs that said there was no difference in amount of time as byproducts and operating debris is what determined when to change engine oil. In the past I had conversations with oil engineers that stated as long as the product had the API and SAE certifications that the manufacturers called for and you changed the oil according to manufacture's recommendations, you would never have a lubrication problem.
     
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  8. kshansen

    kshansen Senior Member

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    Well my 2 cents, which are worth way less that what you are paying for it would be if you are needing to use the Detroits on a limited basis in cold weather would be to put the 15W-40 in when weather gets close to freezing. YES! I know you should not run that stuff in a Detroit! But what is worse starting an engine with thick oil in near zero temps where it will take a few seconds to get any real flow to the bearings or run and oil that will get here right now! This does not take into account the wear and tear on batteries and starter trying to turn over the engine.

    And here is what Detroit said about cold operation of 2-strokes in 1997:
    01.jpg
     
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  9. 1693TA

    1693TA Senior Member

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    I always ran 30WT Delo 100 in my two stroke Detroit engine(s) for a lot of years. I still have a couple of barrels brought home when the gensets were decommissioned and replaced by Kohler sets powered by John Deere four stroke diesels. Still have the gensets and switchgear also on a couple as partial to the 12V-71T series myself. Never any oil related problems and no more leakage than the four stroke varieties of the day.
     
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  10. Birken Vogt

    Birken Vogt Charter Member

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    I guess my recollection was incorrect then. Looks like they wanted straight 40 under all conditions.

     
  11. kshansen

    kshansen Senior Member

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    Yes but I know for many years when we had a few 12V-71's in the R35 Euclids at the quarry we ran straight 1230 Mobil oil in them. I believe that is what the Mobil oil rep recommended. The Cat engines all got 1330 which was what they called Series 3 oil at that time. I'm mainly talking late 1970's to 1980's.

    Of all the various 2-stroke Detroits we had the only one that I recall being way messier than the 4 stroke diesels, like Cat or Cummins. That was a little 4-53 genset that was being run way below rated load and wet-stacked like crazy.
     
  12. crane operator

    crane operator Senior Member

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    I saw he's located in Wyoming, so that was my concern with winter use and 40wt. It can get cold there.
     
  13. Birken Vogt

    Birken Vogt Charter Member

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    Yes, but the only thing in the Detroit snippet posted above (which is what I was misremembering from back in the day too) is that they are concerned about cold startability. I'm sure the OP can figure out how to get it to start, and probably a way to preheat the whole engine, so 40 it is.
     
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  14. Old Doug

    Old Doug Senior Member

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    Have you had any problems dumping that crap in your older engines? There is a time and place to use synthetic oil. From what i have seen it run out in a stream in a old engine that didnt leak any regular oil.
     
    Last edited: Aug 12, 2022
  15. oarwhat

    oarwhat Senior Member

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    Anytime we tried synthetic is an older engine they started using oil. I was always told not to change to synthetic.
     
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  16. John C.

    John C. Senior Member

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    I've run Chevron Supreme in my stuff for years and it is mostly no longer available around here anymore. All I could get for the wife's 4Runner and my Tacoma was synthetic so I changed over and have run it for the last 10K miles. Wife's car has 197K on it now and no oil leaks so far.
     
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  17. Old Doug

    Old Doug Senior Member

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    There is nothing wrong with using syn in a newer rig but there is every thing wrong dumping that crap in a older engine. A buddy bought a 1968 Camaro this spring . He drove it less than 50 miles to get it home it used a quart of oil . I went and looked at it there was half a case of penn 20w50 in the back seat. I put Rotella 10/30 it was also leaking some . It dosent have plates on it so i dont know if that will fix it but i have let it run in the shop and it hasnt leaked any. The engine is a rebuilt 383 it dosent have any miles on it the owner died.
     
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  18. John C.

    John C. Senior Member

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    The wife's rig is a 2002. My Tacoma is a 2013.

    I've heard the same thing for a long time. Maybe the issue is cork and paper gaskets instead of silicone sealant and natural rubber seals opposed to the fancy types used today.

    When I was in the service, synthetics were only used for extreme weather conditions like arctic or desert operations. I'm still thinking the term as used today is just another marketing ploy.
     
  19. Old Doug

    Old Doug Senior Member

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    Marketing is were the money is to be made it dosent have to be great or wright it just needs good marketing. I read about syn oil back in the early 80s it was around $40.00 a quart then.
     
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  20. cfherrman

    cfherrman Senior Member

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    I was always told syn oils are made from better crude oil bases.

    What's great about older engines is store brand 15-40 is a way better oil then when they were made.

    I've had plenty of people run 15-40 in 2 strokes. This is the age old question that there is a different answer for each person you talk to. Me I run 40 weight in mine, 30 when you can't find 40.