Just how important is oil viscosity (the number after the W)

Discussion in '1997 - 2003 Ford F150 Truck Forum' started by geezer08, Feb 19, 2016.

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  1. geezer08

    I have been using 5W30 for.......ever. I took my 2000 Expedition (5.4LV8) in for a plug change. (don't laugh. That engine has fuel injection and was way over my back yard mech skills). I also agreed to an oil change and specifically said 5W30. Long-short. They used 5W20. Should I stress and make them do it over and go back to what has been in that engine since 2002, or just leave it alone. Colorado Springs, CO. Just about to enter Spring, and our Summers can be in the 90's. I will be towing a boat before next oil change due.
    All thoughts/comments are welcome.........unless snide. I am to old to deal with snide.
    Thank you,
    Geezer
     
    geezer08, Feb 19, 2016
    #1
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  2. clux Article Contributor Founding Member

    No way I'd tow in the heat with 20 weight in there.
     
    clux, Feb 19, 2016
    #2
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  3. JWC 3 TOTM Winner Founding Member

    The way I was taught.
    The first number is the pour weight, or viscosity. The second is the protection, running weight.
    The more difference between the numbers the less base oils and more additives to reach the protection level. _
    Flow weight is as important as protection.
    That said, go with what you have used.
    But if your engine calls for the weight they used, dont sweat it.
     
    JWC 3, Feb 19, 2016
    #3
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  4. whomrig TOTM Winner Founding Member Southwest Chapter

    I use the 5W30 as my manual calls for that.
     
    whomrig, Feb 19, 2016
    #4
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  5. FTZ HAIC Staff Member Oregon Chapter Founding Member

    Ford has spec'd everything from 20 to 40 weight in these modular engines, even engines with exactly the same tolerances. So while it shouldn't damage it, and they might not change it because technically it's running a spec'd oil for that engine... I prefer a heavier weight oil.
     
    FTZ HAIC, Feb 19, 2016
    #5
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  6. clux Article Contributor Founding Member

    The
    The 20 weight recommendation is 100% fuel economy driven with no regard for the design of the engine.
     
    clux, Feb 19, 2016
    #6
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  7. geezer08

    I knew someone would school me about the use of the word "viscosity", but that's okay. Never to old to learn something.
    I am generally getting the answer.... do not sweat it. BUT clux seems to think that towing this Summer might be the wrong thing to do.
    Any further thoughts?
    At this point I am letting it go.
    NEXT ???
    I will definitely put 5W30 back in when I change the oil again.
    Any problems with that?
    Thank you all,
    G
     
    geezer08, Feb 20, 2016
    #7

  8. FTZ HAIC Staff Member Oregon Chapter Founding Member

    While I agree fuel economy was a factor as Clux noted, oil related failures are rare on the 2-valve 4.6/5.4 V8s in the trucks. Early versions of these motors, the common problem was spark plugs getting blown out due to too few threads to hold them in, but Ford resolved this.

    Remember though, Ford's 5w20 recommendation is not for conventional oil 5w20, but for semi-synthetic or full synthetic 5w20. Motorcraft 5w20 is semi-synthetic. I would find out if the oil they used is semi-synthetic or not, and base your decision on that. Maybe even consider how heavy the loads are... if you're pushing it close to the maximum rated limit, I'd go with thicker oil.
     
    FTZ HAIC, Feb 20, 2016
    #8
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  9. OldjunkFords Oregon Chapter Founding Member

    I'm not a fan of 5W-20..........pretty thin stuff, one step up from WD-40.
    I plan to change the Escape over to 5W-30 from 5w-20 when summer heat is here and it may be pulling a 15ft boat.
     
    OldjunkFords, Feb 20, 2016
    #9
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  10. geezer08

    You were correct. XO-5W20-DSP is what they used. Premium Synthetic Blend Motor Oil.
    All is calm on the homefront now.
    I'll be changing back to 5W30...... probably.....
    A little more research is in order. Thanks to all.
     
    geezer08, Feb 20, 2016
    #10

  11. Hayseed2016

    Please refer to Ford TSB 99-8-16 for accurate oil recommendations. The XO-5W20-DSP Premium Synthetic Blend Motor Oil is absolutely correct for your application.
     
    Hayseed2016, Dec 16, 2016
    #11

  12. joepro

    Just my 2 cents, I have ran 10w40 in My 97 ford f250 for the last 17 years I was told the thicker oil protected the engine better.so far so good.
     
    joepro, Mar 26, 2017
    #12

  13. FTZ HAIC Staff Member Oregon Chapter Founding Member

    FTZ HAIC, Mar 26, 2017
    #13

  14. clux Article Contributor Founding Member

    The startup lubrication and cold weather issue can easily be address with wider viscosity synthetic like a 5-40 or 0-40 which aren't all that more expensive than conventional oils. And in spec bearings retain oil for startup for a long time anyway regardless of the viscosity. Again, this is about the pursuit of better fuel economy on the bottom end.
    The virtual disappearance of flat tappet engines would most likely explain the ability to use lower viscosity oil successfully, not bottom end bearings, IMO.
     
    clux, Mar 27, 2017
    #14

  15. FTZ HAIC Staff Member Oregon Chapter Founding Member

    Engines also have 10x better machining tolerance than they did 30 years ago. Thicker oils are not needed to fill the gaps. Quite right thinner oil achieves better fuel economy, because there is less friction.
     
    FTZ HAIC, Mar 28, 2017
    #15
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