Engine flush, good idea or more trouble than its worth???

  • hello guys,
    i would like your opinions and experiences with engine flush tratments please.
    i will be servicing my car soon and was considering flushing the engine with something like wynns or similar from halfrauds.
    however i've had mixed reaction to this idea so far. a few have said its ok and works well but i have heard the odd horror story of it creating serious problems that did not exist before!!
    does anyone on here have experience with using these treatments and if so please share, good or bad.


  • I serviced my 2.0 V6 Lantis alot, (imported 323f) and always used an engine flush never done it any harm although when i put a differnt grade of oil in think it was a catrol one the car ran completly shit another service with another flush with mobil 1 it ran spot

    unless the person left the engine flush in with the new oil then maybe that would do some damage lol

    good way to do it would be,

    let the car warm up put engine flush in i think u hold it at 2k-3k revs for 10min
    car off empty oil
    old filter off new filter on with a dab of new oil round the rubber,
    new copper washer for the drain plug
    insert new oil i recoment mobil 1 10w40 iirc
    Also put in hynns HLA treatment as these engines are prone to tappet noise

  • I have never used engine flush as most of the oil will run out if you do it while the engines cold and its been left to stand overnight, just take the sump bung out and leave it running away there will be hardly any old oil left and any that is is not worth worrying about TBH

    The only things that can be a pain is a lot of the breather pipes at the top tend to build up with oil residue over the years and cleaning them out once in its life on an older car is not a bad thing either so the engine will breathe like it was new again, thats simply a bottle brush and some washing up liquid and scrub the pipes through.

  • I didnt have any problems when I used it on my oil change, never had any problems using it on bikes with wet clutches either. For me I think its only worth using when you first get the car, since youve no idea how well it was kept before you got it, once youve treated it, so long as you keep to the oil change schedule, I dont see any need to use it again since youll have been keeping it clean and healthy through the practise of good maintenance.

    Millions of people dont use it and their engines dont breakdown because they didnt use it, millions of people do use it, and their engines dont breakdown. Theres always someone whose had a problem with something, that much applies to every single thing on the planet. But I will say that it could unearth existing problems that you just didnt know about. A pretty common one is with radiator flush products, people use them, then find their radiator is leaking, the product wont have caused the damage as theyre formulated to be safe for the coolant system components, what is likely to have happened is that there was an existing hole, but it was crusted up with the deposits in the coolant, sealing the hole, once the flush is applied, it removes the deposits sealing the hole and hey presto, youve got a leak that was already there but you didnt know anything about.

    The same could easily happen with oil flush, if its moving all the gunk out, that gunk will move along the oil path all the way through the entire engine until its trapped in the oil filter, if something particularly unpleasant or a heavy build up starts to shift around, then it could easily get caught up in the valvetrain or something else, which would then give you a problem, and cause you to complain about it, when it actually did the job it was supposed to, its just that the debris is loosened caused problems.

    When I use flushes, be it petrol, coolant or oil, I never rev it higher than idle, I really fail to see the need. If the product is an effective one, then the detergents and solvents in it will clean the system, it will take a bit longer, but I feel happier knowing that the flow rate is lower and so the amount of gunk it removes at any given moment is likely to be smaller in size and so shouldnt get trapped in anything until the filter.


  • From my own personal experience, i wouldnt do it again. Car ran shit for a month after. Might not be the case all the time but its not worth it to me.

  • I did it when i put in KLDE, left it overnight, put new oil in, 2-3 weeks later big end bearing went, not sure if was related to flush but will never use one again, + side I put a KLZE in :wink:

  • As a mechanic my opinion is of course NEVER use engine flush.

    Especially in older cars as you get a build up of crap (particulary in the bottom end bearings) metal fillings, small bits of crap etc that have built up over the years and are now actually acting as part of the bearing. Engine flush can clean out this all important crap and royally stuff up an engine.

    Sometimes I have used whynns tappet cleaner (NOT THE LIQUID VERSION IN THE BOTTLE ITS TOO HARSH) use the oil version that comes in the can type thing with the ring pull. But only when I had bought a new car and could tell it was clogged and the oil had gone thick.

    But usually when I get a new car I just empty, then run some cheap oil, then empty again and put in decent oil.

    After that regular servicing with good quality oil is all you need.


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