BG or Moc machine for flush?

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I am going to get some synthetic ATF for my Lexus. On the GS400, you can't really drop the pan because it's glued and not meant to be removed. Also, it doesn't have a filter but a mesh screen. If I do a drain and fill only 2 quarts are removed and the capacity is 8 1/2 quarts. If I did 10 drain and fills I would still have about 8% of the old fluid still there and so I was thinking about a flush. The Lexus dealership doesn't do flushes and so I called the two Toyota dealerships and they both have a flush machine. One of the machines is a BG and the other is a Moc. Is one necessarily better than the other? Is there another route that will remove most or all of the old ATF? The vehicle has about 126,000 miles and shifts smoothly.
 
They are both about equal in effectiveness, so don't worry.

Also, it DOES make sense to drop the pan every once in a while. Some stuff sticks to the pan that can only be removed by cleaning the AT pan with solvent and drying it with a rag. If you think it is held in by glue, it means it uses RTV sealant instead of a gasket to hold fluid.
 
The old way was to siphon what you could and fill. That would work for a glued on pan. You would need a few cycles to get the % of new ATF above 80%. Not a cost effective way to do it.

I would say you can/should do a cooler line flush yourself. A helper to stop and start engine is always good. Easier and cheaper than you think. Get 3 feet of 3/8" clear tubing at HD. Undo one of the lines at the connection going to the cooler and connect the clear tubing, stuff the other end into a clear gallon container. Start the engine (for a few seconds) and see what happens. You may need to try the other hose. Drain 2 QTs into a clear gallon container. Stop the engine. Add 2 QTs. Continue cycle until the fluid changes color or you get the total amount needed cycled through + 1 QT. This will use the least amount of your expensive synthetic ATF.

Most flush machines are the same. They accept the old ATF being pumped out and pump fresh ATF into the pan at the same rate its coming out. The transmission's own pump does the real work.

If you have a flush done at a shop, ask them to empty the new fluid container before they add your synthetic ATF. The machine will not pump to empty, so a QT of your expensive ATF will be in the machine when you are done. You will probably need 3 extra QTs of your ATF if you use a machine.

I like Amsoil ATF, feel its top shelf stuff. But its your choice. If you have a flush done, ask them to forget the cleaner & conditioner. Not needed.

Its always good to install an inline Magnefine filter. Best $20 you can do for your transmission.
 
For fun you could build your own flush machine. Think about what materials you have available and what else you would need. It's very likely that the rubber hose and clamps will be the majority of the cost if you're only counting materials.

What do you really need for a simple build? Well, you need a rigid or semirigid container such as a pail or a pipe; a means of separating the container into two chambers that can easily trade volumes without mixing such as a diaphragm or piston; suitably sized flexible hoses; a means of attaching these hoses to the container. Difficulty: using only materials that will not deteriorate in the presence of ATF. Cheat: separation of the two chambers need not be perfect considering that some mixing will occur inside the trans anyway. Bonus points: use only new materials and keep the price tag under $20. Note that if using this pumpless type system you'll want the total volume of the container to be as close to the volume of new fluid you intend to use, but not less.

For 3X bonus points post pictures.
 
Why does one need two chambers capable of trading volumes? Why can't they be two independent chambers? If there is no suction available at the intake side, why can't one raise that chamber little above so that gravity will help?
 
Guys, thanks for all of the informative posts and responses. When I called the dealership with the BG machine, the service person indicated that "xxx amount of pounds of pressure are used to flush the old ATF " and that worried me a tad with all the horror flush stories online. Both places will also use some kind of cleaner in the flush process and not merely ATF. The vehicle takes 8.4 quarts and the dealership told me to bring 12 quarts---does this sound right?
 
Originally Posted By: Vikas
Why does one need two chambers capable of trading volumes? Why can't they be two independent chambers? If there is no suction available at the intake side, why can't one raise that chamber little above so that gravity will help?


I was just suggesting one possible design. The idea is for the total to remain the same so that as the trans pumps into the 'waste chamber' a nearly equal volume is pushed from the 'fresh fluid' chamber back into the car. Obviously the compressibility of air and the hoses being empty except for air mean the fluid level in the trans will drop somewhat, but not all that much.

Your approach using gravity is just as valid.
 
Originally Posted By: Capa
Guys, thanks for all of the informative posts and responses. When I called the dealership with the BG machine, the service person indicated that "xxx amount of pounds of pressure are used to flush the old ATF " and that worried me a tad with all the horror flush stories online. Both places will also use some kind of cleaner in the flush process and not merely ATF. The vehicle takes 8.4 quarts and the dealership told me to bring 12 quarts---does this sound right?


They were giving you the usual uneducated response. The machine does NOT and CANNOT flush the fluid through the transmission. Its the pump in the transmission that does the work. The machine only uses a little positive pressure to pump new ATF into the pan of the transmission, NOT through the transmission. There is just no way the machine can do anything else. As I said, forget the cleaner, BG company pushes the cleaner and a conditioner as a sales add on, you do not need either. Ask them to purge the new ATF container of fluid before they add your synthetic. In one case, they were surprised, but over 1 QT of new ATF was left in the new fluid container when the machine was finished with the prior vehicle. Who knows what spec ATF it is. If you want to really do a super job, add some Auto-Rx and go 1000 miles then have the flush done. Many people here don't feel it does a good job in the engine, but do feel it does a good job in the transmission. I have it in the transmission of my Dodge Ram right now. And ask or bring a Magnefine filter to be installed. Yes 12 QTs sounds about right.
 
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