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Thread: Sludge

  1. #1
    I am not Michael Jackson Array jako's Avatar
    Join Date
    Aug 2004
    Metro Vancouver
    Honda F4i


    Question.... are motorcycles subject to engine sludge like cars? I know that our family van needs to have a engine flush every 3rd oil change cause the oil is so black. If bikes have sludge issues too, do we put engine flush additive in before we change the oil?

    I am thinking not because the bikes rev much higher than cars.

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  3. #2
    Moderator Array TeeTee's Avatar
    Join Date
    Feb 2002
    Out to pasture in the 'Wack
    04 Kawi Z1000,
    Sludge comes not from lack of revs but from lack of oil changes at timely intervals.

    If your family van is one of the newer ones that says it can get away with oil changes at longer intervals then this is the problem. Change the oil and filter at 5K kms and to hell with what the manual suggests. Sludge buildup is a sign that the oil is not being changed often enough and you have exceeded the ability of the oil to hold the crap in suspension.

    Back in the 70's I bought my first new car and changed the oil and filter religiously at 5k km's. 3 years later when I tore the engine down totally to race prep it for sedan racing at Westwood the insides were spotless bright metal with no signs of black deposits. It was a pleasure to work on it like this.

    Oil is a wonderful "detergent" if you give it a chance. Even a sludgy engine will perk up and clean up with more frequent oil changes without the need for useless and possibley harmful flushes. The flush oil is very thin and may not have the film strength needed to prevent metal to metal contact in the bearings.

    This is all based on the assumption that you're doing your own oil changes and not depending on some kid at Mr Lube that shows you a dirty oil dip stick and recomend that flush. Oil after even 5K will be darker but if you tip the container to one side the oil on the sides should be dark but still with a sign of the original brown color to it rather than more of a grey'ish black. or pure black opaqueness. Dark as hell but still with a bit of transparent brown tint to it is fine. The oil has not reached it's limit to hold the sludge in suspension. But beyond that it can easily be a differnt story.

    At least that's my story and I'm sticking to it...
    A backyard mechanic without a service manual is just like a hooker without a lamp pole.... they are both in the dark.

  4. #3
    this is my...boomstick! Array CrotchetyRocket's Avatar
    Join Date
    Aug 2002
    click, click
    The threat of "sludge buildup" in cars and bikes is a sales pitch to sell more oil and more chemicals.

    Sludge is a function of poor engine condition, a damaged crankcase ventilation system, incredibly extended oil change intervals or fantastically long idling engine periods. Modern EFI engines have very good crankcase fume control and very tight engine sealing, due to materails and design advances. This just does not happen in normal use.

    I guarantee that "engine flush" you're putting in there is doing more damage than the black oil is, as long as you're observing an even remotely reasonable oil change interval. Basically, engine flush is Varsol or similar and engine bearings don't like that stuff too much.

    Stop using this crap, change the oil/filter every 10K max (car, standard dino oil) Do the same on the bike, save cutting down the change interval a bit if you beat on it, and you'll be fine and will never, I repeat, never, have an oil-related engine failure.


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