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  • 3 Post By techinspector1
  • 3 Post By 34_40
  • 2 Post By Dorsey

Thread: Oil weight for an older engine
          
   
   

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  1. #1
    Dorsey's Avatar
    Dorsey is offline CHR Member Visit my Photo Gallery
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    Car Year, Make, Model: 29 Ford Hi Boy Roadster
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    Oil weight for an older engine

     



    I'd been putting 10w-30 into my engine for the past 25 years. The engine is a 400ci SBC from a mid-70s GM truck. Not clear if it ever been rebuilt, as there were no records when I bought the car. I suspect not - it was more likely picked from a junkyard, hosed down, and painted to match the car.

    I read a recent magazine article by somebody resurrecting an older hot rod (a barn find). Part of the process was draining the oil and filling the engine with 20w-50. Have I been doing this wrong? Are the older engines designed for the heavier weight oil? The oil pressure has always been low, in the 30-35psi range.

    Thanks for help and opinions.

    Dorsey
    Dorsey

    There is no expedient to which man will not resort to evade the real labor of thinking.

  2. #2
    techinspector1's Avatar
    techinspector1 is offline CHR Member Visit my Photo Gallery
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    I see no reason to change. Keep doin' what you're doin'. And there is nothing wrong with 30-35 psi as long as you aren't drag racing and buzzing the motor to the moon.
    .
    PLANET EARTH, INSANE ASYLUM FOR THE UNIVERSE.

  3. #3
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    Car Year, Make, Model: 34 Ford 3W Coupe Replica
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    Times 2, 30-35 psi is perfect for a 25 plus year old motor. Don't change a thing.
    Many guys think the higher number / thicker oil is better, but that isn't actually true for a street car.
    In many cases, the "thicker" oil actually causes stress / strain on motor components like oil pump drives etc. ,
    You've been doing it right for 25 + years - keep up the good work!

  4. #4
    Dorsey's Avatar
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    Thanks, all for calming me down. It's a low-stress engine in a car (pictured) used to run errands and cruise the hot spots at low speed.
    Rrumbler and glennsexton like this.
    Dorsey

    There is no expedient to which man will not resort to evade the real labor of thinking.

  5. #5
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    I think you should cruise over here and take me for a ride!!! rotflmao! 8-)

  6. #6
    fraso is offline CHR Member Visit my Photo Gallery
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    Engines need oil flow and pressure is a characteristic of flow and viscosity. If you increase your viscosity unnecessarily, you could end up causing more flow to recirculate back to the sump through the relief valve. I would use a 10W-30 heavy duty engine oil (I use Petro Canada Duron SHP 10W-30) in my engine with a dual rating (ie, API CK-4/SN) that also meets Ford F1WSS‐M2C171‐F1 (for more ZDDP).

    Your donor truck's owner's manual would likely have called for 40-grade oils in summer temperatures. You can easily use any 15W-40 heavy duty engine oil and this grade's higher HTHS viscosity will give your bearing more protection. See Corvair Oil Guide and Engine Wear.
    1965 Barracuda
    Rods & Relics - Fort Erie / Collector Car Tech

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