pktaske

...no need to ever change fluid under normal driving conditions?

I read this after I had already drained my Tran oil.

Weird....

hypervish

Toyota doesn't officially recommend changing the transmission fluid unless driven in severe conditions.

However, dealerships themselves have advised their customers about changing the fluid every 15k - 30k miles due to the failures they were seeing first hand.

The Toyota T-IV is by no means a lifetime fluid (neither is Toyota WS, no matter how much they want you to buy into it being so). In fact, I think the T-IV is one of the reasons why these transmissions can fail. T-IV is not a very stout fluid, I no longer recommended using T-IV. I'd go with an alternative such as Castrol Transmax IMV, or an Amsoil product.

salimshah

Do you want to know why or find it strange and get opinion on how often to drain/fill?

Salim

pktaske

Sure.

Note I used Castrol Transmax IMV.

salimshah

Here is the explanation of why [others may or may not agree with it]:
Purpose of the transmission fluid is to lubricate and provide the mechanical coupling (with give) in the torque converter. The mechanical loss, turns into heat. Torque converters have a lock (stall speed) and at higher speed the two sides get locked and there is no mechanical loss (no heat). Under "normal" driving conditions the temp never gets very high.

For lubrication, the transfluid makes it circuit and keeps a layer or oil on all moving parts. Any wear of mechanical parts is carried down to the pan and the pump sucks the the trans-oil from the top of the pan.

Note: Engine oil gets subjected to burn bye products and over time you need to drain it out and put in fresh oil.

In the transmission case, there are no bye-products. Under normal circumstances, only thing the transmission oil gets degraded is due to worn metal it carries.

Based on the above, what Lexus [and many other manufacturers] recommend is a drain to exit out sediments and increase % mix of fresh fluid.

There are all sorts of speculations and if you must pick the one that makes you happy. I have been reading this forum for a while and I can give you counter examples to all reported cases. Even down to at least two failures that happen right after drain and fill.

I have tried to list possibilities in the sticky .. mega thread ... start here.

Not too long ago people were happy if their transmission lasted over 100,000 miles.

Salim

pktaske

Makes sense but mechanically tranny oil can break down over time and while not as hot as engine oil, it does get up there. I had big problems with my 2007 CRV and it turned out to be the trans fluid:

http://www.crvownersclub.com/forums/...ph-solved.html

If you're going to say your trans fluid never needs to be changed, you better be darn sure it can hold up that long. That old Honda fluid was a 20 year old design - they recently changed it in 2010.

salimshah

Not to mislead any one, I do a drain and fill at an average interval of 20k miles and did a pan drop (+ inspection) at 100k miles and have stayed with Toyota Type IV.

Theoretically, there is no breakdown of transfluid [unless the fluid reaches its shear temperature ... abnormal condition]. Usually it is something else, like component grind down that pollutes the fluid ,,, needing refreshing. Or something that hinders circulation, like pump or clogged filter etc.

The auto-trans is more complicated than the engine itself. Most owners think it is the transfluid (they have the most control on it), but it is very unlikely the root cause of the problem.

At the end, I would say it again ... choose what ever lets you sleep at night as the best prevention/cure.

Salim

dbui

Salimshah,

My 2001 reach 185k and I did not drop the trans pan yet, original owner, but it had been drain and fill every 15-20k should I drop and replace the filter or leave it alone and continue the drain and fill schedule?

Thanks for your input.

salimshah

Do drain and let the vehicle remain with the pan on for few hours.

I would suggest that you drop the pan and remove the sediments and clean the magnets and inspect the filter. If you have a paper-like element, then it should be replaced. Most likely you will find a metal screen and that can be cleaned and reused.

Few things to remember .. the magnets must be placed on the same location you pull them up from. Use a toque wrench to evenly put the pan back on.

Thomas is our resident expert on transmissions. So do take his input over everybody's.

Salim

Arden

Does anyone has a picture of the metal screen.
I would like to have an idea how it looks like, and how to remove it for cleaning purposes.

Thank you,

salimshah

From the bottom you cant tell them apart. Once you remove the filter, then you can see the metal mesh (fine screen) or paper-like element.

Salim

hypervish

You can see pictures of both the mesh and paper filter here: https://www.clublexus.com/forums/rx-...ns-filter.html

Arden

Thank you, I guess, The screen mesh can be removed manually from the top.

salimshah

If you are in Australia then yes.

When you drop the pan and crawl under .... the filter bottom (all metal of either types) will be visible. Once you unbolt the filter, then you get to see the screen.

Another way to visualize is that the filter skims the fluid from the top of the fluid in the pan.

Salim