Running Hot...oil that is, good or bad?

Discussion in 'Propulsion' started by brian eiland, Jun 22, 2012.

  1. brian eiland
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    brian eiland Senior Member

  2. Submarine Tom

    Submarine Tom Previous Member

    Run the correct viscosity for your operating temperature.

    No need to get all fancy.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Motor oils have become quite sophisticated in recent decades. I don't think the gains suggested will materialize in average daily use. Jacking the oil temperature as much as 50% will break it down faster and test the viscosity limits, leading to more frequent oil changes. Amortizing the costs of this unit, particularly in light of the added costs of more frequent oil changes, would place it out of the average original purchaser's window of ownership, so it's a lose economically, as an OE offering.
     
  4. DCockey
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    DCockey Senior Member

    A few years ago there was considerable work being done in the automotive industry on getting lubricants up to normal working temperatures as quickly as possible in order to reduce losses and improve efficiency. My recollection is transmissions/transaxles were a major focus of this effort because the losses in transmissions, particularly automatic transmissions, associated with lubrication viscosity are consider higher than in engines. I don't know the current status of these efforts but given the significant increases in fuel economy required in the future I expect they are continuing.
     
  5. gonzo
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    gonzo Senior Member

    The automatic transmission fluid is cooled and heated through the radiator. The engine warms faster and warms the fluid, when the transmission works harder and heats up, the radiator cools it. It is not the most efficient method, but has worked well for several decades.
     
  6. DCockey
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    DCockey Senior Member

    Correct. But how quickly the transmission fluid and engine oil heat up is signficant. Fuel economy for regulatory and window sticker purposes is measured in transient tests which start with the entire vehicle at 70 F and last around 20 to 30 minutes. So how fast the transmission fluid and engine oil reach operating temperatures has a significant effect on losses and therefore fuel economy.
     
  7. Submarine Tom

    Submarine Tom Previous Member

    Pre-heat your engine and/or use a multi-grade oil.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Engines and transmissions come up to temperature in a minute or two, unless idling in cold weather. So, in regard to a 20 minute test, a 5% improvement in warm up speed, but in reality, fairly insignificant in the big picture. So, the net gain of a few percent in engine or transmission efficiency across the 5% warm up test period, seems a wee bit like nipping at the edges, if you ask me.
     
  9. MechaNik
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    MechaNik Senior Member

    What a load of misleading hocus pocus.
    Nothing mentioned in the article about speeding up the heating only increasing the temp.

    Anyone thinking of changing the operating temperatures or viscosity of their lubrication oil had best learn a bit about modern lubrication (Most notably hydrodynamic lubrication) before they ruin some parts.
    The resistance they are so eager to do away with is a necessity to establish anti-wear lubrication, as oil is not just there to make it turn easier.
     
  10. DCockey
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    DCockey Senior Member

    The systems I was aware of (not the one in the linked article) provide a measure improvement in fuel economy. I'm not aware of any vehicle manufactuers adding equipment to speed lubricants reaching working temperatures, but I've been out of the industry for almost three years. However, an improvement of 0.1 mpg for a vehicle is significat for a manufactuer which needs to meet fuel economy standards. For the individual consumer that difference may not be as significant.

    For boats the situation is somewhat different, though I won't be surprised to see engine makers pay more attention to lubricant temperatures if engine efficiency becomes more important.
     
  11. WestVanHan
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    WestVanHan Not a Senior Member

    My diesel pickup truck,even at just above freezing levels (5 degrees C) I will let the engine idle for a minute,then slowly drive off.
    Within 100 meters the transmission temperature gauge is showing it's usual operating temperature....so in this instance I don't see how any transmission warming will do anything.
     
  12. brian eiland
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    brian eiland Senior Member

    I would think this thought should be given greater consideration. But if oil is there to reduce friction (turn easier), then that friction reduction should equate to less wear?

    It would be interesting to see how much extra 'friction' is created by the engine parts moving thru the oil fluid.....some dry sump verse wet sump subjects, etc
     
    Last edited: Jun 24, 2012
  13. Submarine Tom

    Submarine Tom Previous Member

    Molyslip is a German made product I used for years in race car engines, even turbos, but have never tried in marine applications. They make a gear oil additive and an engine oil additive. The active ingredient is molibdonim(SP?) sulfide.
     
  14. Frosty

    Frosty Previous Member

    A truck engine or a marine engine is not under stress. All this oil talk is feeding strawberries to a pig.

    Many fancy oils do nothing to improve the performance but does improve the interest of the man in the street that knows no better.

    Some people would use synthetic in a cement mixer.

    Molyslip was used 40 years ago and was before silicone additive. It was to reduce friction noise in gearboxes and diffs. I cant believe you can still buy it,--refer to above.
     

  15. MechaNik
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    MechaNik Senior Member

    There are many different types of load bearing surfaces ie ball bearings, bushes and gear teeth.
    The bearings of greatest concern in an engine are those extremely highly bearings of the crankshaft called journals. The advantages of this type of bearing being used here are such that I can't think of a modern engine that does not use them.

    Now although there is some metal on metal contact at stages ie startup the bearing works by running on a metal oil interface or hydro planning in layman terms. We refer to this as hydrodynamic lubrication as opposed to boundary lubrication. In boundary lubrication the oil fills troughs in the surface finish but ultimately there is still significant metal to metal contact.
    How long do you think a journal bearing plate would last with metal to metal contact knowing that it is made of soft lead and copper?

    So some things that will affect your journal operating correctly are tolerances in fit (wear), oil pressure, rotation speed and viscosity of the lube.

    If someone can tell me how efficiency is improved without changing the viscosity or load bearing properties of the oil then I too am interested.

    Now there are and always will be special this and that for racing engines, but those guys hardly blink before rebuilding an engine.
     
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