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Engine and gear oil levels

Discussion in 'The Garage' started by JpEater, Feb 24, 2006.

  1. JpEater

    JpEater 1/2 ton status

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    What are everyones thoughts on raised engine oil levels and axle oil levels. Trying to find out if it helps or hurts? Some people say add one quart extra to the engine and as much extra as you can get in an axle.
     
  2. readymix

    readymix 3/4 ton status

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    I always fill engine to spec and the axles as much as I can
     
  3. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    more oil in a motor does more bad than good. don't put more than spec, unless you have a bigger pan.
    i try to put as much as i can in the axles as well, without putting too much in.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I tried to get an answer on the diff oil, but couldn't.

    Overfilling the engine is bad because you start whipping the oil up into a froth as the reciprocating parts contact it, plus the drag from the parts trying to move fluid.

    I don't see why that situation is any different than an axle, unless the gear oil doesn't "froth" so easily. How can overfilling an axle be good? The axle tubes alone will hold a bunch of fluid, but is having the entire axleshaft and bearings bathed and trying to turn in fluid a good thing? Does it hurt or help gears to mesh submersed in fluid vs. having a decent coating? Why wouldn't the manufacturers put the fill plugs up higher if it was a good thing?
     
  5. readymix

    readymix 3/4 ton status

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    In an engine the crank is not bathing in the oil. No need at all for that since there is an oil pump.

    The opposite is true in an axle application.

    Sure the gear oil can froth a little bit, but think of the differences between axle and engine bearings.....
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Sure there are differences in the bearings and applications of the two, but if gear oil froths up, doesn't that still decrease it's effectiveness?

    I'm kind of thinking of those cheesy lucas oil displays you see at the auto parts store counters :)...the gears pick up the lube and hold onto it as they mesh, (visualizing ring/pinion here) so a) what advantage is there to overfilling, b) if the gear oil froths up, will it be as effective once the gears mesh, c) will the lube be picked up by the gears as easily, and d) isn't overfilling wasting power?

    Obviously an oil pump can't pump air, so frothy engine oil is a big no-no. :)
     
  7. readymix

    readymix 3/4 ton status

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    I am sure that it would make the rear end less effective as far as oiling and lubrication goes. But I am not sure if it would froth up any more than normal if you overfilled it.

    The parasitic loss however would increase as you said. Not sure by how much though.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    yeah, it's more curiousity than anything, but it is pertinent to the posters question. I'm just thinking of the aftermarket diff covers that have the fill plug way up high.

    With the axle tubes full I can see an axle taking a TON of fluid, but you then end up turning every axle component in fluid at all times, which just doesn't seem good.

    I know someone that killed her engine because she overfilled it with oil, haven't heard of axle failures from being overful though. :)
     
  9. readymix

    readymix 3/4 ton status

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    Yeah I have seen a few engines damaged from too much oil. Never heard anything about axles though.
    I have been putting as much as possible in all mine for years
     
  10. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I have an additional thought to add. Bear with my as my theory may have no merit.

    As far as I can tell, an engine is designed to work properly with "x" amount of oil being pumped through the sytem at "x" PSI by the oil pump. If you increase the volume of oil in the system, the overall PSI within the system can actually be increased as well. This is due to the fact that the additional oil will create a backlog of pressure as it tries to drain back down to the pump.

    Basically, the extra volume causes extra pressure because the additional oil can't run through the sytem fast enough. And extra pressure can harm seals, etc...

    Does that make any sense?:crazy:
     
  11. readymix

    readymix 3/4 ton status

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    It makes sense....but I don't think that you could apply that line of thought quite that easily. Look at it this way.

    The engine oil system is sort of a closed loop system....sort of.
    The air space available also makes it like an open loop system.

    If it was a true closed loop system that adding extra oil would have the exact effect you described. But, because of the air space available, the extra oil is just there. Not really hurting anything.
     
  12. beater_k20

    beater_k20 Banned

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    agreed. once the oil reaches the rod bearings, or in the case of oiled piston pins, it is simply dropped back into the sump. on the upper end of things, ince it reaches the rocker arms, it drains down the holes in the cylinder heads, into the lifter valley, through its drain holes, back to the sump. no real chance for building extra pressure.
     
  13. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    So then what would be the big deal if you wanted to run an extra litre or two in the crankcase? :confused:
     
  14. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    Windage
     
  15. 79Beast

    79Beast 1/2 ton status

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    Both axles and engines fill to a spec for a REASON. Thing is, when we lift a truck, it generally changes the pinion angle. On a FF14 or similar axle the fill plug on the pinion snout, the oil will overflow at the same "level" no matter what the pinion angle. On a Dana/Spicer style axle with the fill plug on the cover, you have exactly the opposite problem. The more pinion angle you have, the less oil you can get the axle to hold. I usually use a floor jack to lift one side of my front D60 with 8 degree shims so the the fill plug is higher and I can fit a little more oil in it to make up for the angle.
     
  16. beater_k20

    beater_k20 Banned

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    go outside, and take off running. now go to the nearest body of water, and wade in to your knees. now take off running again. same exact thing your crank will be doing with extra oil in the crankcase.
     
  17. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    From the article you linked to:

    Geez, I can't recall the last time I had the ol' K5 wound up to 6K......:whistle:

    So Jeremy, you're not serious when you imply that an extra litre of oil would affect performance by approximately a third.........or are you??? Come on, I'd appreciate it if someone could give me a thorough explanation of exactly why one or two extra litres of oil in the system is bad for the motor.
     
  18. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    Learn by experimentation - try it and see what happens.
     
  19. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    That's kind of a cop out, isn't it? :dunno:

    FWIW, I'd rather not use a 23 year old 305 with 180K on it as a "guinea pig".....
     
  20. beater_k20

    beater_k20 Banned

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    i dont recall saying that it would rob 1/3 of the engines power. the running in knee deep water was an easy comparison. i will say one thing... you have a 305, not the biggest powerhouse on the block, and i'm going to assume you have highway gears in it. go ahead and add your extra oil. just remember, when your crank starts sucking up that oil in the sump, you're robbing power, causing the engine to work harder to move the vehicle. and an engine that is working harder is consuming more fuel. expect to see your milage drop significantly with the potential loss of power.
     

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