hugo2648

I am very close to buying a 2000 Lexus RX300 with 111K miles.

I was planning to get a transmission flush done. But some tell me
that it is not a good idea to get a flush done - especially if it
has never been done before. A better way is to just drain the fluid,
clean the filter and be done. But that probably replaces only 1/4 of the fluid.

I would really appreciate the list's opinion on this.

Lexmex

Well, first thing I would check is the nature of the existing fluid. It is red, sweet in smell? In addition, does the seller have records of transmission service with regard to the fluid and what intervals were they.

I have done a flush once and in that case I had silvery/pinkish fluid (indicating wear), had it flushed at a Lexus dealer in Florida (my home state) and vehicle felt wonderful afterwards.

Generally, 3 drain and fills over the course of 3 weeks will change out a majority of the fluid.

Meetya

Completely dry transmission (including front differential) requires 8 quarts of ATF. Draining true pan gives about 4.5 quarts. I have no idea how much draining the front differential gives. Make sure to drive around for 10-15 minutes (preferably on a highway) and start draining immediately after it. I comes out better if it is warm (it should never get hot enough to burn your hands).

Lexmex

I found it is at least .5 liters or so with that front differential from experience.

TunedRX300

9.8 quarts for dry fill for AWD. I disconnect the tranny cooler line and get out about 7 quarts of ATF in one shot.

Meetya

No way! I won't argue about the dry case (it will depend on how dry it was plus I doubt my shop extracted everything from radiator).
But 7 quarts for a cooler line? How much there is in the radiator? At most 1 quart. You probably also drained pan and differential, right?

salimshah

Lexus service says drain and fill. Frequency is debateable.

The fluid is in a closed loop and there are no chemicals that get added to it [Engine oil keeps getting chemical by the burn action of fuel].

Things that can go bad with the trans fluid are:
Thermal breakdown.
Aging.
Solids from mechanical parts.

A good portion of transfluid is in the pan, convertor, chambers and the rest in pipes and radiator. A drain and fill essentially increases the volume of fresh vs old oil. If you do repeated drains and fills, it takes 11 turns to get 99.99% fresh fluid. Within 3 you get a substantial portion of fresh fluid and at roughly 6 times it is above 95% [all this is based on my recollection of a post]

The level above drain and fill would be dropping the pan and cleaning the magnets + hard sediments (the ones that do not flow out) out of the pan. One can change filter too.

The next level would be the flush. The problems with flush is you dont want to dislodge particles and bring them into circulation (hard sediments in the pan etc). A safer approach is to use the pump of the trans to pump the old trans fluid out and at the same time equal volume of fresh fluid.

My personal view is that one should not stir up things un-necessarily. If there is a problem, then sure go ahead but if there is no problem dont go about creating one. People have reported problems but the RX is not plagued by transmission problems. Those who have experienced the problem, may disagree with me. We all see things from our vantage point.


Salim
ps: I am not incouraging to ignore a problem. So do check the status of fluid.

Lexmex

Salim brings up a very important point on sediments and this is something one can see on the magnets in the tranny pan as shown. I have no doubt more is inside the transmission as I mentioned in another post tonight that in the process of helping my uncle on the weekend, we encounter such sludge in trannies he takes over to his buddy to fix.

HarrierAWD

Flushing isn't a good idea. Check the fluid level and color first. Do 2 or 3 drain-n-fills will take care of it. If it's an AWD, the total capacity is about 9.8 quarts. A simple drain through the plug will get out 4 quarts. Dropping the pan or disconnecting the cooler will get some more, though not worth the hassle IMHO. The filter can last a lifetime.

I recently did 3 drain-n-fills and this was what it looked like. The right most is the fresh fluid. Be sure to use Toyota Type T-IV or equivalent.

TunedRX300

9.8 is what says in the shop manual.
The tranny cooler has less than a quart. I drained out about 5 quarts from tranny pan and xfer/front diff plugs.

Transmission is a closed system, so the containments stays in the system until drained. Tranny filter is more of a screen, the more one drains out the system, more debris get out.

Meetya

Guys, I would recommend to replace transmission filter. If you change the it, go with OEM, it is not expensive.There are two aftermarket brands available from Autozone and O'Reilly those top part is made of HD-polyethylene as opposed to steel OEM. Don't use aftermarket. Polyethylene has tendency to degrade very quickly at warm temperatures and can [will] crack eventually (take a look at your coolant extension tank and other tanks under hood -- do you know which color it is supposed to be?). I know stuff about plastics.

TunedRX300

I ordered OEM replacement tranny filter form Lexus Park Place in Plano TX. The top part is also plastic, here is the thread with pictures.
https://www.clublexus.com/forums/sho...d.php?t=220061