Got a call from my wife this am. She had drove her 99 RX300, w/48000 miles, earlier with no indication of a problem and parked it in the carport. When trying to leave later on it would not engage reverse.

Upon responding to my urgent summons and arriving home I discovered you could feel the slight clunk when putting the RX in reverse but the engine simply revved when applying the gas. There was no whining sound or anything. Drive would engage so I pushed it out of the carport, put into drive and headed down the driveway for an expoloratory drive around the block.

At first there was a whining sound and then a clunk. Ater the clunk the noise disappeared and everything was normal, even in reverse. Several trips around the block stopping to back up yielded nothing abnormal.

I called my service rep back who said to just drive it, that unless the check engine light was on it would do no good to bring it in for service because nothing would show up. He said not to worry that the transmission was covered under the drivetrain warranty and if it happned again to go ahead and bring it in though. Makes me feel real confident, know what I mean?

My questions are 1- Has anyone had or heard of anything like this happening and 2- Is this possibly the beginning of a transmission failure that will probably happen after the warranty has expired. You thoughts and comments are appreciated.

 

The same type of problem happened to me on Friday. I have a 99 with 92k. I felt a clunk when I put it into drive and pressed on the gas. So I put it back into park and tried again. It did the same thing. Drove it around the block. It did not repeat. I ended up taking it to the Dealer for its 90K service. They changed out all the fluides. Cost me $400, but it has given me some peice of mind.

 

I have heard this several times in my 99 with 57K. That was before I switched the ATF fluid to Toyota Type-IV synthetic. The Lexus mechanic said that whatever Lexus dealer was filling the ATF fluid before was putting regular Dexron-III in it, likely Castrol. While not entirely bad for most cars, it is for a Lexus. He also said you could not go wrong using Mobil 1 ATF. Have it changed and make sure they put the right stuff in.

 

I too have the 99' RX300 w/ 44M miles which recently started making a clunking noise only when trying to engage in reverse. I made several trips to the dealership in town and they keep assuring me that nothing's wrong and gave me the same speech about the drivertrain warranty.....

I insisted on talking to a factory rep. So, we will see what happens. I will keep you guys posted.

 

I want to change my fluids this weekend. Anyone else think that Mobile 1 ATF is okay for the transmission fluid?? I haven't seen anything that states that Mobile 1 ATF can be used in place of T-IV so I am holding off until I have confirmation. I would rather use the Mobile 1 if it is not an issue sin ceI doubt the T-IV from Toyota is synthetic even though it should be at their prices.

What about Mobile 1 75W-90 for the gear boxes? Doesn't quite have the viscosity specs listed in the manual but I think it would suffice. Anyone using it?

 

I don't think there is a "working" substitute for Toyota Type T-IV. I have been searching for years on the internet and everywhere. I have read it somewhere - I think it was a Toyota bulletin, that in case of an emergency like rapid transmission fluid leak/loss, that you can use a Dexron type-- but only to get you to the dealer/repair shop for service. In that same bulletin, it was advised that using Dexron for a long time will eventually lead to transmission problems due to fluid properties not designed for specific pressures and viscosity properties called for by Toyota/Lexus transmissions. The Type-T-IV is the only fluid that should be used. (By the way, it is not a synthetic oil. Type T-IV started life as a Dexron and then further modified by Toyota to suit their transmission needs).

In my opinion, if you want Lexus to cover the transmission warranty (70,000 miles or 72 months), use their recommended fluid (check the manual). Test and learn about Mobil-1 when factory warranty on the tranny expires.

 

In early January this year, my wife and I were driving home on the highway in our '99 RX300 AWD and the transmission just crapped out. The engine was still running and it was in drive, but no forward propulsion. We had it towed into the dealer and they replaced the transmission and transfer case under warranty. My wife had mentioned to me a few days earlier that "it was acting funny" but there was no real warning. In hindsight, it may have been slow to upshift when cold, but no real signals that there was a problem. It had ~57K on it when this happened and it was the first problem we've had with it.

The check engine light came on today, so I guess the honeymoon is over...

 

Just got my 99 RX300 back from Aamco today. $3700.00 poorer, but it runs. Check the thread under "Not Happy" for other unfortunate transmission stories. Seems this is not all that rare.

 

My '99 had no tran. problems at ~50k, serviced at dealer for recommended changes of whatever fluids they used.