Engine Oil Question (s)

Discussion in 'Chemistry' started by river, Jun 5, 2016.

  1. river Valued Senior Member

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    Can anybody tell me what makes a very good engine oil and why ?

    I have 2014 MustangGT , 5.0L .

    It is recommended that I use ; 5w-50 .

    Thoughts
     
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  3. river Valued Senior Member

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    This thread is the real thread on this topic .
     
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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    To get such a wide viscosity range, there must have been some "trade-offs," and more expense to you. Unless you live where it gets very cold, you don't need the 5w end of that range. Something like 10w - 40 should be fine in the winter and in summer, 20w - 50 if you do a lot of hard driving that gets the motor hot but for most, 20w - 40 should be OK in summer and I think that is cheaper.

    Changing between these two every 6 months may cost a little more than annual replaement of 5w -50 but keeping the oil clean, free of dirt is important.

    You can not evaluate it, but good thermal stability/ no chemical changes with heat/ makes a "good engine oil."
     
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  7. exchemist Valued Senior Member

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    Be a bit careful about the W spec. Modern engines often use smaller starter motors than traditionally, as this allows smaller batteries, both saving quite a bit of weight and thus aiding fuel economy. You may find cranking in cold weather with a 20W is too much for some of these, even in temperate conditions.
     
  8. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Use what the manufacturer recommends. Unless you change internal parts of your engine you shouldn't use anything other than what they say.
     
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  9. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Thanks. I did not know that. I had a more than decade old VW beetle, and when its starter motor failed, I did not replace it. There was hill both near my house and at work I parked on - It always strated the car before the bottom of those hills arrived.
     
  10. exchemist Valued Senior Member

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    Yeah there is something of a move to lower viscosity generally, in the search for optimum fuel economy. Pumping viscous oil around is generally wasteful of energy. If the tolerances are tight you don't actually need a very high viscosity. But it all depends on engine design. In general I would always follow the handbook for a modern engine. With vintage beetles etc it's another story. (Just don't put antifreeze in them! I heard of someone who did. Ethylene glycol screws up lubricating oil - turns to jelly, and goodbye engine. In fact, Shell used to make a special lubricant to stop that happening, for British Rail high speed diesels - Paxman Valenta V12 - that at one time suffered a chronic leakage of coolant into the oil system.)
     
  11. timojin Valued Senior Member

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    How would ethylene glycol get into it . unless the block is cracked
     
  12. exchemist Valued Senior Member

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    The engine in a VW beetle is an air-cooled flat four.

    But occasionally, some idiot would put antifreeze into the only filler cap opening they could find on it......with hilarious consequences......
     
  13. sideshowbob Sorry, wrong number. Valued Senior Member

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    A friend of mine had to stuff blankets around his beetle engine to keep it warm when it wasn't running in winter. Here in Canada we have block heaters (which some of you may have to Google) to keep our coolant warm. I don't know if they have much effect on the viscosity of the oil.
     
  14. iceaura Valued Senior Member

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    They do. And it's important. Probably more important than the effect on the coolant. That faster, easier spin from the starter is almost all oil viscosity benefit.

    The trend to lighter weight oils, a consequence of both higher fuel efficiency expectations (the stick) and closer achieved tolerances in standard manufacturing (the carrot), has fooled me a couple of times. I have switched to lightweight but durable synthetic oils in a couple of high mileage engines, and had the experience of the small extra bypass loss leading to gummed up and sticking piston rings, which in turn leads to larger bypass loss, and so forth. Feedback.

    But very nice for cold weather starting, among those of us doomed to park outside and drive old cars.
     
  15. exchemist Valued Senior Member

    Messages:
    6,477
    Yes it will definitely affect the viscosity and this will have a marked effect on ease of cold cranking. That's what the "W" part of the viscosity classification is all about and why it is so important. In Canada you can even go below the "pour point" of the oil if you are not careful - that is the temperature at which the wax in the oil sets solid!
     

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