Hello everyone,

My 2008 RX350 will hit 163k miles. The previous owner didn't do any transmission fluid service. I would like to do it now since the car shakes after shifting to 1st gear and there is a delay from 3rd to 4th. This happened recently after my speed sensors went off, which I replaced, but the problem is still there. The fluid color is dark but has no burnt smell.

I've consulted with a mechanic who advised me not to do it because there's only a 50/50 chance it might fix the problem or make it worse since the fluid wasn't changed before. That's why I didn't perform the service before, but since the car is now acting up, I feel I have no choice.

So I wanted some opinions on what to do now? I believe if I don't do the flushing and change the fluid, my transmission will fail.

 

The trans is probably shot regardless of what you do. A simple drain and fill of part of the fluid may be a safer alternative to a full flush with that many miles. This will refresh the fluid a bit and often results in some shift improvement. However are you thinking of installing a used transmission when this fails?

 

Idk, how long do I have left before eventually changing the transmission? I might have to get a used one or just get a new car instead because I have more repairs in the future.

 

AWD or Fwd?

 

You’ve received some really bad info from the mechanic. And off the top find a better mechanic than the one you consulted. He’s a hack. The symptoms can (of a few options) trace to low line pressure, and that can be addressed.

1st, have you verified the fill level is correct? Also know, putting clean fluid in a trans will not kill it. Old wives tale. Bad mechanics use that excuse to avoid trans work, because they are usually crap at it and ignorant of how transmissions actually work on a practical basis. Does putting fresh oil in an engine kill it? Would you skip changing oil in an engine if overdue, and just drive it to the ground? No.

- Drain and fill the trans 1x, add some solvent to it like SeaFoam or a little B-12. This will treat bad seals and clean varnished bores, potentially restoring function. Verify fill level w/car running. Don’t obsess about the temp, idling a few minutes to warm is adequate.
- Drive it a week to two and see if it improves.
- If so, do a further 2x drain/fills or a 9 to 10qt cooler line swap (better). use an ester-based oil or additive (like Lubegard) to continue gently seal conditioning and cleaning.

The first step costs $30 and could save your transmission, why not do it? Also, you have no CEL light/codes, correct?

 

Oro is spot on regarding the incompetent mechanic and misinformed service. I asked about AWD or FWD as if it is AWD this service is VERY easy, very cheap I cannot comment on FWD. These trannies (not to be confused with a Bruce Jenner Tranny) shold have their fluid changed probably every 60K as it is easier to do than the engine oil and filter changed every 100K. If it was not done since new then change it a few times over te next few hundred to thousand miles as you only remove a portion of the older fluid each drain. Not sure that will rememdy your issue but fluid adn filter shold be under $30 and labor should be more than $100 at most (just to change the fluid takes minutes, to change the filter less than an hour).

Shaking is not likely the transmission, sounds more like engine mounts

 

Leeper thank you and it's FWD. It's not shaking actually I meant a strong vibration when it shifts to 1st gear/2nd gear.

Thanks Oro I'll look into it, if not let me see if I can get it checked by someone else or the dealership. Looks like he just wanted to get the trans changed for the extra $$$.

 

RX known to have rough shifts in this gen. Do a drain and fill. Clear the ECT to reset the transmission learning again

 

Thank you I'll do that then. The rough shifts started happening after the speed sensor went out.

 

I'll second that rough shift from first to second.
Mine is an 05 RX and we've had it ten years. Had that issue the whole time.

If the first step helps, I'd look at gradually switching over to a premium ATF like Amsoil, unless you prefer the Toyota OEM oils.
I use Amsoil in all my trannies.

 

aside from marketing what makes you believe that Toyota or Valvoline Maxlife ATF is not "premium?

OP - change your fluid you have no idea when it was last done or what they used... that is extremely cheap and easy clearl;y what fluid you use is up for debate. Read the many threads on that to draw your own conclusion. If you're a DIY'er it takes less than 15 mins or so to do it, if you also want to change the filter trans flter that takes a bit more time but I'd highly suggest doing so. Again remember changing the fluid only removes @1/4 of all the tranny fluid so repeat the process a few times over a few hundreds miles to get most all the old fluid out.

 

Don't believe I ever said I didn't think Valvoline Maxlife wasn't premium.
Just stated what I preferred to use.

 

If the first step helps, I'd look at gradually switching over to a premium ATF like Amsoil, unless you prefer the Toyota OEM oils.

That statement would infer that the latter is not premium

 

Which still doesn't say anything about Valvoline Max Life.
You did read what you quoted, didn't you?

 

Use Toyota Transmission oil, you will not regret it. Using something else is very risky.