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Switching Oil Viscosity

Discussion in '80-Series Tech' started by Imagery, Sep 9, 2003.

  1. Imagery

    Imagery

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    I would like to switch to Mobil 1 whatever weight may be suggested in the previous posts on the topic... I will look over them to make sure but I think someone said it is best to use something like 5w-40 in Mobil 1. A friend said that he heard it was bad to change viscosities once a motor is used to running a certain weight. Is this true??
     
  2. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Cary can probably speek to that best but I'll take a stab. I think not because the owners manuals publish viscosity ranges for usage based on ambient temperature and make no mention of using only one weight.


    Dan.
     
  3. cary

    cary

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    It is an old wives tale. For years people would run 20w-50 in the summer and 10w-30 or 10w-40 in the winter. Just use the Mobil 1 0w-40 year around. If you have consumption issues then go and search out Mobil Delvac 5w-40 at a truckstop.

    Cary
     
  4. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Cary,

    What's the wives' tale, staying with one weight "because the motor is used to it" or changing weights for significant temperature changes? (pre-synthetic, of course).


    D-
     
  5. cary

    cary

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    The old Wives tale is changing weights will harm the motor because "it gets used to it." These are the same guys that don't understand that from -10F to 200F 10w-30 changes thickness by a factor of 300 (Goes from about 10 Centastokes at 200 F (operating temp) to 3000 centastockes at -10F).

    Also don't forget that a 10w-30 synthetic is no thinner than a 10w-30 mineral at the -25C low temp test . If the synthetic was thinner it would be called 5w-30. That said at very low temps (i.e. -50c) the synthetic 10w-30 may continue to flow while the mineral will not, but it is so thick as to be not pumpable anyways.

    Mobil 1 0w-40 is the way to go because it is the same thickness at -40C as 10w-30 is at -25C. On the other end, the 0w-40 is about 40% thicker than the 10w-30 at operating temperature.

    Cary
     
  6. Pskhaat

    Pskhaat

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    [quote author=cary link=board=2;threadid=5122;start=msg39578#msg39578 date=1063156208]
    consumption issues then go and search out Mobil Delvac 5w-40 at a truckstop.
    [/quote]

    Why does the Delvac help consumption?
     
  7. cary

    cary

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    Delvac 1 is slightly thicker than M1 0w-40, both at starting and operating temperatures. It seems to help consumption a bit. Also, sometimes some cars just don't agree with certain oils, if you have a car that consumes 1 quart every 1000 miles on one oil another brand in a differnent weight may drop the consumption in half. I have not had any trouble with consumption with the 0w-40, so far having burned 1/4 quart in 2000 miles.

    Cary
     
  8. Pskhaat

    Pskhaat

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    Cary, what are your thoughts on straight 30 weight oil? And is there such as 30-40 or 20-40 (not 20-50) for extraordinarily hot climates/conditions? You've talked about combining different weights from the same brand...
     
  9. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Mercury Marine has a 25w40 oil for I/O engines. I run that in my 4.3 GM powered Chaparral. They claim it is for severe service. I guess 4800 rpm WOT runs constitute severe service.
     
  10. Pskhaat

    Pskhaat

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    I've always wondered about using an ashless dispersant 40 weight aircraft oil. I'm always interested in the quality of aircraft parts and just read this the other day:

     
  11. cary

    cary

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    Here are my thoughts:

    1) Straight weight oil- Don't waste your time. There is no advantage.

    2) 20w-40- Not any thicker than 0w-40, 5w-40, 10w-40. For extrodinarly hot climates you would step up to a xw-50 oil (there shouldn't be a need though). The reason that you don't see 20w-40 anymore is that the other multi viscosity oils take its place. So why did it ever exist? Because back in the dark ages of multiviscosity oils, the viscosity modifiers and pour point depressants needed to make a mineral oil multiweight would break down quickly and cause sludge. The wider the oils weight span the more modifiers needed the more sludge created. In the past 30 years the base stocks for mineral oil and the viscosity modifiers and pour point depresants have improved considerably. Today there is really no problem with sludging from viscosity modifiers and pour point depresants. They still break down, but much slower and without the crud left behind. Synthetics tend to need less of these additives and it is widely speculated that Mobil 1 10w-30 does not in fact have any viscosity modifiers or pour point depresants (note this is different than detergent)

    3) Aircraft Oil- This is completely different than auto and truck oil, just like aviation gas is different than pump gas. DO NOT MIX CAR STUFF AND AIRCRAFT STUFF, IT IS A RECIPE FOR DISASTER. Just a few items, aircraft use leaded gas and no cat converters, no 02 sensor, and have entirely different service conditions and intervals. The oil for aircraft would likely destoy the emisions system in an automobile because of the different additive packages. In fact the change from API grade SJ to SL was not to improve the lube qualities but to lower additives that damage emissions equiptment.

    Also the guy who is being quoted about synthetic being to slippery doesn't know his ass from a hole in the ground.

    Cary
     
  12. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Cary,

    My, my, wouldn't it have been nicer to say that he couldn't find his bottom with both hands and a flashlight at high noon? ::)
     
  13. Pskhaat

    Pskhaat

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    [quote author=cary link=board=2;threadid=5122;start=msg39938#msg39938 date=1063225503]
    DO NOT MIX CAR STUFF AND AIRCRAFT STUFF, IT IS A RECIPE FOR DISASTER. Just a few items, aircraft use leaded gas and no cat converters, no 02 sensor, and have entirely different service conditions and intervals.
    [/quote]

    I have to remember this is an 80/100 series area, but my question pertained to F/2F completely desmogged engines BTW.

    I just looked it up on google a while ago and deleted the URL when posted. Wonder why Mobil AV1(or whatever their aviation oil was) didn't make it then?
     
  14. MTNRAT

    MTNRAT

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    Warm engine, Drain penzoil 10w30 oil, remove filter and replace with new filter, replace with new mobile 1 oil. :D :D :D :D :banana:
    Cheers
    Sean
    "I could not help myself" :D :D :D
     
  15. Imagery

    Imagery

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    [quote author=MTNRAT link=board=2;threadid=5122;start=msg39958#msg39958 date=1063228165]
    Warm engine, Drain penzoil 10w30 oil, remove filter and replace with new filter, replace with new mobile 1 oil. :D :D :D :D :banana:
    Cheers
    Sean
    "I could not help myself" :D :D :D
    [/quote]

    Thanks guys... This has ben very educational and I believe I have a good understanding about different types of oil and viscosities. I am going to drain the Penzoil this weekend, get a case of Toyota filters from the dealer, and go back with the M1 0W-40. Thanks for the great advice.

    Mark
     
  16. Jonathan_Ferguson

    Jonathan_Ferguson ★ is in the wrong locale SILVER Star

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    SAE 20W/40 is a very common Oil(Especially for Mixed Fleets), Such as on a Farm. - Penrite Universal Farm. :flipoff2:

    How about for an Engine that operates in a consistant Enviroment, Where the Temperature and R.P.M. is constant. :flipoff2:
     
  17. cary

    cary

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    [quote author=Jonathan_Ferguson link=board=2;threadid=5122;start=msg40121#msg40121 date=1063250890]
    :flipoff2:How about for an Engine that operates in a consistant Enviroment, Where the Temperature and R.P.M. is constant. :flipoff2:
    [/quote]

    That is true, but I don't think that automobile motors qualify for that. Oh, I should mention that since you are down under, you should be using 40-w0 because everything is backwards. :flipoff2: :flipoff2: :flipoff2: :D :D :D

    Couldn't help myself.

    Cary
     
  18. cary

    cary

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  19. Jonathan_Ferguson

    Jonathan_Ferguson ★ is in the wrong locale SILVER Star

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  20. lovetoski

    lovetoski SILVER Star

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    Question on Delvac for Cary

    Cary,

    If I understand, Delvac is a type of Mobile 1? (I went to the "Delvac" page on Mobils' website - but I'm not a chemical engineer!).

    In a higher milage cruiser engine, well maintained, but with higher oil consumption (1 qt per 300-500 miles, but strong compression) would Delvac be advised or not?

    Thanks for your advice,

    Doug Graham