pilot2

When I owned a Volvo, a common trans flush method was to disconnect a trans cooler line, connect a hose to the line and run it to a bucket which you have marked with a 2-quart line. Start the engine and allow 2-quarts to run into the drain bucket, stop engine, put 2-quarts of new fluid into the trans. Repeat process until clean fluid was coming from the drain line. I understand the correct fitting to disconnect for the draining procedure is in the picture below (a prior picture posted depicted the wrong line). if disconnected, the fluid will flow-out of the rubber portion of that line. Is there a reason this would not work just as well on an RX? Wouldn't this procedure be better than just draining-out and replacing 4-quarts?

salimshah

Nothing unique here. Similar process is posted here.

The process is essentially the same as repeat drain and fill (with an exception, which I will list in the last para below). What is accomplished is the fluid in the converter and cooler is also replaced.

What it does not do is remove the sediments which are collected at the bottom of the pan.

Salim

hypervish

There is a DIY for that here: https://www.clublexus.com/forums/rx-...er-change.html

Some people do it, nothing wrong with the method. I like to introduce new fluid slowly, and I rather do it every 10k miles so it's continually being done. Rather than a flush at longer intervals.

pilot2

I had seen that post, the differences being: 1) it has the added steps of removing and re-installing two drain plugs, the system I outlined, no need to pull any drain plugs--only disconnecting one line for the whole flushing project and 2) I would attach a clear hose to the rubber Lexus line using a barbed brass push-in connector as shown in picture below to make the logistics of the job easier. Needless to say, the end result should be as close to a 100% fluid change as is possible without putting any flushing-machine stress on the system.

I am not suggesting the foregoing is a substitute for occasionally pulling and cleaning the trans pan and filter, I am speaking of all the interim trans fluid changes between the pan/filter procedure.

artbuc

I think you can accomplish both. The first thing I do do is drain the pan after driving with the engine at normal op temp. This gets the sediments. Then fill the pan with fresh fluid before you start fluid transfer.

pilot2

I wonder if there is a standard valve that could be inserted into the trans line referenced such that with the valve in one position the fluid is flowing through normally and in the alternate position the fluid is redirected out another port to which a drain line would be connected. Thus, the system, irrespective of whether you also pulled the drain plugs, would be to simply turn the valve, collect two quarts, stop engine, poor-in two new quarts, repeat as necessary.

salimshah

There are drain plug adapter available [for the engine oil pan for sure]. You can have one machined. Just be aware that down there, things can snag and catch on to the modified plumbing.

From manufacturer's point of view, they opt to provide some convenience. Lots and lots vehicles do not have a drain plug on the transmission pan. Reason is that transmission fluid need not be replaced or partially replaced at 60/80/90/100k miles (pick a number). It is like rear diff oil, which needs to attended to very infrequently. There are no contaminants getting in the fluid.

I personally follow the manufacturer's recommendation where replacing the majority of old fluid at one time is not done. I have shortened the interval a bit and at 100k dropped the pan [not required].

At the end, do what makes you happy/comfortable. There is no direct co-relation between tranny failure and % fresh fluid.

Lastly doing a trans & front diff drain is lot easier than changing oil filter in RX.

Salim