Photo DIY: RX300 AWD Transmission Fluid, Pan, Filter Change
So I'm going to follow the procedures in this thread AND install (replace) an auxiliary oil cooler, a fan (from an atv) that will switch from a relay triggered by the OE coolant fan thermoswitch (if there is one, if not I have one I can use) and an inline filter (Ford truck filters on ebay run $5). That will be my attempt at extending the life of the trans.
I've also learned that the RX shares internal trans components with the Highlander, Camry and Sienna. I didn't find anything here on Club Lexus, but wondered if anybody had seen reference to doing the internals swap. With the price of used RX trans running over $2k, this would be a very viable alternative. Given the popularity of the camry, low mileage trans it are sub $1k. Just move the guts to the RX fwd case and you're good to go.
thanks- rob
I bought my wife a 99 RX on March 4, 2008 so she can drive around the kids and keep them out of my truck for a while
. It has 83,300 miles and I don't have any service history on it so all lubes have to be changed very soon and now that I got some really good info I should get to it in the next few weeks.Trans oil right now is nice and red and smells good but I don't know if it was just changed for a cover up to sell vehicle. It shifts fine. One thing I learned about this truck is that if it's cold out it will not shift from 2nd to 3 until about 3k rpm's, it still shifts smooth. Once oil temps go up it shifts smooth and at 2k rpms or less if I'm easy on the throttle. I have read many different horror stories on these transmissions breaking down and want to try and prevent it from happening.
Question, I have close to 100 qts of mercon III/V ATF, if I wanted to drain the trans and used the stuff in the RX trans for a few hundred miles then drain again do you think I will be doing more harm to the trans than good.
The toyota/mobil stuff is red and so is mercon and come to think of it so is my blood when I bleed, but I know I can't use that.

I really am planning on cleaning out the filter pan, magnets, cooler lines and then refill with the mercon. Then maybe go about 500 miles with it, then maybe do it again for another 500 miles. So after about 1000 miles on the mercon I will go into the toyota/mobil ATF as described then go 1k miles and finally change it again with a new filter and toyota ATF. Is this too much, I have no idea if the previous owner ever changed it so I want to do a super clean job and I have all those qt's sitting around.
Wow nearly wrote a book here. These BLEEP newbies don't know when to stop.
Again great job on both threads.
Last edited by 6.0PSD; Mar 25, 2008 at 07:42 PM.
As far as using the other fluid that you mentioned, I would recommend against it. Reason I say that is from experience down here with mechanics (and even one Toyota dealer (not the one that I know thankfully)) have used something other than Type-IV Toyota fluid and came out with some unfortunate results in at least 3 Camrys and 1 ES300 (of a friend many years ago).
TunedRX300 and others have used Amsoil ATF, which I plan to use when I get back to Florida in under a month and some have used Redline's ATF and I believe we have had a few use Royal Purple, but with those other synthetics I haven't heard of any horror story and in the case of Amsoil I have heard great things.
My respects to your F250, it is one of the more popular trucks that has shown up at my track here, always a pleasure to have them.

If you really don't think I should risk driving a few hundred miles with the other stuff then I'll clean out the trans as described here and flush with the mercon, refill trans with it, do a drive around town(small town of South River) for a couple miles to warm up the oil completely and then drain, clean trans pan again replace filter and flush adding then the toyota Type IV or the others mentioned here.
I'm still confused and wonder, if Toyota created that number IV to throw people off from buying other ATF's that are available for much less at local parts stores. I guess no one will really know for sure unless you work directly with the toyota plant and/or oil supplier. Does Toyota want their customers to keep buying their product???????????? I'm just wondering
Thanks again, Philip
Celebrating Lexus & Toyota from Around the Globe
Well, Mobil makes that fluid for them. The Toyota Type IV is used on a set of the last generation of Toyota/Lexus products, but not newer Toyota/Lexus products are using WS (World Standard fluid), has slightly different characteristics.
I know that not all transmissions are so twitchy with other fluids, my uncle and his buddy work on trannies all the time, but these Toyota trannies aren't the cream of the crop in my personal opinion. However, based on experience, I know my uncle will attest to worse problems on Honda/Nissan transmissions. The buddy who helped fix my tranny last December sees an inordinate number of Honda transmissions in his place.
jon
Thanks, I am glad it saved you money. It has been two years plus a summer since I changed 7 quarts and so far zero trouble. I will soon do a drain and fill and likely will send a used ATF sample for testing and post the result in another thread.
I was wondering if there is a different part number for the metal version of the filter instead of the paper?
What size are the bolts holding the oil strainer? I couldn't find it in the 1st page.
My last question would be, what's the estimated fluid I need if I do all the above without the cooler line process?
4 qt(drain) + 1 qt(front diff) + ?? (pan + strainer)?






