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Hot Rods Whats the pro and cons on flushing out old oil with engine flush

Discussion in 'The Hokey Ass Message Board' started by Bruce Fischer, Mar 9, 2017.

  1. I know I will catch a lot of flack on this but when I pulled the dist. out to replace the points and condenser on the 56 chrysler because it was so hard to get to I noticed some sluge oil on it and after I get the carb. rebuilt I was wondering about an engine flush. I have read when it lossens everything up and motors run better and then where it gets rid of the gunk but can cause the oil pump to get clogged with the gunk and seals that have been protected by the sludge have started leaking. I also notice when I shut the motor off some smoke comes out the oil filler tube. Now when the carb was working good the motor ran like a top. So let em loose whats your guys advice? Thanks. Bruce. P.S I don't have a lift so dropping the oil pan would be a problem. 011.JPG
  2. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 26,431

    Jalopy Joker

    pull the valve covers and post pics
  3. Bruce, I have never done what you are posting about so I am not much help. However I would think it could clog up the oil pickup on the pump. Hope someone has some insight on this for you.
  4. crossthread
    Joined: Mar 9, 2006
    Posts: 103


    I have had some good results with using high detergent 10w30 diesel oil .With a 4 or 5 hundred mile drive between changes . The diesel engine oil will work fine in you older engine. Been using it in old farm tractors and my gas welders

  5. hotrodyankee
    Joined: Jun 27, 2016
    Posts: 304


    Hi Bruce, getting out all the old hard and soft sludge will be hard to do, unless you take it apart. Using he engine flush stuff might do it more harm then good, in my opinion. I would remove valve covers and get a better idea what it looks like. Mike. Old cars, always some thing! Don't ya just love it.
    scrapiron and Bruce Fischer like this.
  6. Gearhead Graphics
    Joined: Oct 4, 2008
    Posts: 3,799

    Gearhead Graphics
    from Denver Co

    Like you said and others said. Theres potential of getting some out and it running better, and theres potential of causing clogged pickup, or new leaks.
    Look under the valve covers and see what it is.
    Most likely, if it runs good now, leave it alone
  7. Gray Ford
    Joined: Oct 18, 2008
    Posts: 491

    Gray Ford
    from Illinois

    I agree with Crossthread ...That's the method I've used for years .....Be SURE to drain it when it's HOT....I wouldn't even pull the valve covers if they're not leaking ... Like everyone says ....You don't want it THAT clean .......As far as the smoke out of the filler tube, as long as you don't see any when it's running, it's not an issue ...Remember ...How long did the car sit before you got it ????
    Bruce Fischer likes this.
  8. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 3,030

    from Dublin, OH

    Many, many years ago a friend and I used Gunk engine flush on a 326 Pontiac engine.
    The engine was a high miler, and we knew that it did not get regular oil changes.
    We followed the directions to the tee, and then the trouble began!
    The engine was far worse than we would have ever suspected.
    After about 20 minutes it began to smoke out the tailpipes, really badly, fogged the neighbor hood to the point the police were called!
    The engine developed a number of leaks and a little rattle from within that gradually grew louder.
    Bruce Fischer and loudbang like this.
  9. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    Having worked at an automobile dealership, we often had to flush the oil system because the lifters would rattle. We would run the engine with the old oil to get it warm. Add a quart of transmission fluid to the old oil. Run it at idle for an hour. Drain the oil and replace the filter. Install the drain plug. Add 2 quarts of transmission fluid, don't start the engine, let it sit for 15 minutes, drain it again. In a 5 quart system, add 3 quarts of a high detergent oil and 2 quarts of automatic transmission fluid. Start it up, take it outside and let it idle for a couple of hours. Drain it and change oil and filter again. We had customers bring their vehicles in for oil changes and there were no ill effects.

    The ones that didn't quit rattling were usually clean when the lifters were replaced. One exception was a vehicle that the owner used Amsoil and didn't change it very often. It was like melted plastic. The valve covers were completely full and the oil pan was so built up it was full with 2 quarts.
  10. daliant
    Joined: Nov 25, 2009
    Posts: 684


    Don't run anything through that engine other than motor oil unless you want to do an unscheduled rebuild. All those flushes do is loosen up carbon and shit you dont want down in the oil pan which eventually clogs the pick up screen and starves the engine for oil which will wipe out the bearings. So please don't do it, there's nothing to gain.
    cosmo and Bruce Fischer like this.
  11. steinauge
    Joined: Feb 28, 2014
    Posts: 1,507

    from 1960

    Bruce I have dug a number of old tractors and cars and such out of fence rows and gotten them running.If I was not going to pull the pan I put fresh oil and a pint of marvel mystery oil in them ,get the engine good and warm and drain and change the oil.I do that a lot at short intervals-couple of hundred miles after the first time- until I start getting pretty clean oil out.Then I put whatever oil I am going to use in and drive the thing.Always worked for me.I would emphatically NOT use any kind of flush! What the gentleman said about the old Pontiac is exactly the experience I had the one time I ever used a flush.
    Bruce Fischer and BradinNC like this.
  12. This may surprise you, but this question has been asked and discussed about...100 times. There was probably a thread 2 weeks ago.:rolleyes:
    wbrw32 and Bruce Fischer like this.
  13. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 646

    Jack E/NJ
    from NJ

    Yeah, maybe a few hundred times even! So just use a pint or so of MMO and don't ask any more questions or how it works. You'll feel better that you're doing something about the sludge even if you don't know why. 8^) Jack E/NJ
    Bruce Fischer likes this.
  14. I have learned to pull the oil pan and clean the pan and intake screen. and use good oil ( I use 15w 40 rotellat). If you use good oil you don't have to add anything to it. and change the oil and filter at regular intervals. Add a FRANTZ oil cleaner and you can remove a great amount of sludge. All adding some kind of detergent will do is break loose crap and hard carbon. the hard carbon will really score the crankshaft and embed into the bearings.
    Racer29 likes this.
  15. 45_70Sharps
    Joined: May 19, 2010
    Posts: 331


    Yep. Marvel mystery oil in a couple times.
    A bit more for the fuel system.

    Sent from my SM-G920V using The H.A.M.B. mobile app
    Bruce Fischer and KoolKat-57 like this.
  16. BradinNC
    Joined: Mar 18, 2014
    Posts: 213


    If you have a set of good jackstands, pulling the pan shouldn't be a huge undertaking. As long as you don't mind getting dirty. I like to use some big pieces of cardboard to lay on.
    Bruce Fischer likes this.
  17. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,495

    Rusty O'Toole

    Do yourself a favor and don't do it. Use a good name brand 10W30 motor oil with zinc additive. Change oil and filter regularly and don't worry about it.

    If the car has been out of commission for a long time you might want to change the oil, take it for a a few long drives and change it again after 1000 miles. Then go to a regular 3000 mile schedule. Cars with carburetors need more frequent oil changes than modern EFI cars.
    Bruce Fischer and Gr8laker like this.
  18. gene-koning
    Joined: Oct 28, 2016
    Posts: 2,330


    Bruce, Your old Chrysler has a road draft tube to vent crankcase gasses. Until you close up the road draft tube, the oil will always be dirty, and sludge will be there. The smoke coming out of the filler cap is simply air coming up through the road draft tube, through the crankcase, and coming out the fill tube, hot air rises.
    There is a kit available to eliminate the road draft tube and replace it with a pcv valve. After doing that, change the oil and filter a few short mileage changes with a quality oil and enjoy the ride. Gene
  19. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,458


    Have you ever crawled under a 1956 New Yorker on jackstands? I'd rather slide down a mile-long razor blade and land in a vat of lemon juice than to pull the pan off of a 56 N'Yorker on jackstands.
    73RR, pat59 and Bruce Fischer like this.
  20. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,035


    Nothing whatsoever that is not engine oil belongs in a crankcase.

    I have personally witnessed several people ruin perfectly good engines by using some cooked-up flushing scheme.

    If you are not going to tear it down and do it right, just keep doing regular oil changes, with the next two being at 1/2 or even 1/4 interval.
  21. Gary the car was running before I bought it and had had the trans rebuilt not too long ago.There isn't any smoke coming out of the filler neck while running.Thanks for the in put.Bruce.
  22. crossthread I will try that.I guess tractor supply or farmers coo op would carry that?Thanks Bruce.
  23. WOW! Koolkat. I guess you just answered my question what NOT TO DO.Thanks. Bruce.
  24. SOTTY X38 I didn't catch that thread.Bruce.
  25. BradinN.C. been doing it most of my life. I have two 5 ton jack stands from my shop back in the later 70s and still work great Its just at 63 it harder to get up off the floor now. LOL. Bruce.
    BradinNC likes this.
  26. Add a pint of MMO and drive it normally for about a week. Change the oil and filter, also like the idea of a high ZDDP oil.
    Bruce Fischer likes this.
  27. Ebbsspeed, like I said I have two 5 ton jack stands and I also leave two jacks under the frame when I get under the 56 Chrysler but i still get a little shaky when I crawl under that beast. LOL. Bruce.
  28. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,458


    ^^^^THIS^^^^ All any of the "flushes" do is loosen stuff that you really don't want circulating through your engine. Some of the metallic particles that result from normal engine wear are carried out of the engine during normal oil changes, but there is also a lot of metallic particles embedded in that goo. Why set them free and let it circulate through the engine?

    Bruce, it's not so much a concern about being under the car, but rather that removing the pan with the motor in the car is no fun.
    Bruce Fischer likes this.

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