cruzn*k

Had my 1999 RX-300 service by a non dealer shop that is ASE certified and claims to be an expert on Lexus vehicles. I had 45,833 miles on the car and the mechanic put in 4 qts of ATF Mercon 3 fluid in. I heard that this may cause some damage to my transmission. Is the T-IV fluid a necessary for my Lexus? Also, if I do have to change the current fluid to T-IV, must I have the trans pan removed and all the Mercon 3 drained?

toy4two

Get it out ASAP. Bring the guy some T-IV to replace it from Toyota.

salimshah

My post got lost.

There are two issues ... incompatible and wrong. Wrong obviously is when the new does no meet the required standard and incompatible means when the two (Toyota Type IV and Mercon) can not coexist. Sorry I can't comment on either and you will have to call Lexus dealership to confirm.

In case you find out that the stuff is incompatible or wrong, do a drain and fill 5 times and you will be 95% + with toyota Type IV. Just drive 50 miles or more between drain and fills.

Do a search and you will find that with about 11 times drain and fill you get 99.9% of the new stuff. 7 times was 95%+. You have a head start as what you have now is a mix of Toyota Type IV and Mercon.

Salim

Big oops!: I just re-read your post and you state 4 Qts. Wow? Drain and fill is barely a qt. If a flush was performed you would need more than 5 drain and fill or another flush.

rxdriver

Like the others have said, T-IV is a must.

I used to get almost 4 quarts out of the trans on a drain and fill. Back then, T-IV came in a 4-liter can, and I always used exactly one can.

Lexmex

Make sure that on the ATF, they pull the drain plug on the tranny pan (plug on right) and on the front differential (plug on left).

HarrierAWD

Yes, Toyota Type IV or equivalent is required. You'll need to get an ATF flush. Go to a Lexus or Toyota dealer.

toy4two

I would go find a place that will do a full flush, get all that wrong fluid out of there, fill with I-V and repeat in a month. All on the shop's dime. Either that or sell that time bomb, the Lexus tranny is very picky about using Type IV.

salimshah

We know that Mercon 3 is not Toyota T IV.

But

Where can it be determined if Mercon 3 is equvalent or better or worse than T-IV?

Salim

RMMGS4

iTrader: (5)

The correct oil is determined by Lexus stating to use ONLY Type IV approved, that's it. Mercon is not going to ever state equivalent or better because they are "not approved".

This is because the issue is not concerning the quality of the oil, it is about the compatibility of the oil with the mechanical design of the transmission. Lexus designed their transmissions to work with Type IV ONLY.

Look for a Type IV seal of approval stated on the oil container, which you are not going to find on Mercon, Dexron, Type A , Type F or any other typical oil found at your local Kragen or Pep Boys.

The oil you have can eventually cause damage and will void any warrantee. The dealer can flush the tranny. Forget the drain refill process, you need to get all the bad oil out of there ASAP.

A full flush done right is the right thing to do.

salimshah

Does the same apply for synthetic and another popular brand Amisol (sp?)?

Salim

mikey00

ATF Mercon 3 might actually be better than T-IV and maybe even prevent your RX trans from failing as so many are with T-IV. But I don't think anyone here can provide the answer to that. If you feel lucky go for it.
However if it were me I would use the recommended T-IV for piece of mind, if nothing else. I would get a flush to get all of the Mercon 3 out. Usually it's only Toyota and Lexus dealers that use T-IV and you may have trouble finding one with a flush machine. Initially Toyota and Lexus did not embrace the flush concept. I don't know if that has changed by now. The other thing you could do is follow the procedure where you disconnect one of the trans cooler lines to have the trans pump out the fluid.

nthach

Glen is right and so is HarrierAWD - DexronIII/Mercon has no business in a Lexus tranny. Only aftermarket oil that can be used safely is Mobil ATF 3309, since Ford and Mazda also call for Toyota Type T-IV fluids in the Five Hundred/Fusion/Montego/Milan and Mazda 3/6. I'm, skeptical about Valvoline MaxLife ATF and Amsoil ATF although they claim compatibility with T-IV.

Fern

Amsoil states in writing compatible with T-IV fluid (in fact, I believe the AMSOIL universal trani fluid indicates that right on the container).

There have been CL members who have done a complete change over to Amsoil with success...

Don't mess with fluids which are not specifically labelled as compatible, or you may end up paying the price.


cruzn*k,
would your mechanic be willing to stand by the fluid.... say 10,000 miles down the road when something self distructs , or would he be the kind of person that would say something else caused the mechanical failure?

It appears that with all the talk of failing tranis some CL folks may have shifted their focus into thinking T-IV may not be as "suitable" as Lexus is indicating ... That thinking is wrong!

A manufacture is never going to recommend a fluid which is not compatible or which over time, they have seen may cause damage to the trani...

I am curious however as to why toyota on some of the newer vehicles, ie: forerunner, has incorporated a new world standard trani fluid,
better than T-IV ?
Compatible with T-IV?
Why the change?

Just things that make you go hmmmmmm?

rxdriver

ATF-WS has a lower viscosity than T-IV, especially when the fluid is colder. According to Toyota, that reduces drag and improves fuel economy. It is NOT compatible with T-IV; don't ever mix the two or use one in a trans that's designed for the other.

The same thinking applies to the switch from 5W-30 to 5W-20 motor oil. Anything to eek out another 0.5% of fuel mileage.

RMMGS4

iTrader: (5)

The Amsoil Synthetic is approved for Type IV requirements. They can't list it if Toyota didn't approve it. http://www.amsoil.com/StoreFront/atf.aspx

This is one of the few fluids approved by Mercon, Dexron, Chrysler, Honda and so many others all in one formula. I think that says a lot about the product.

I have had my tranny completely flushed with amsoil synthetic and so have several other of my local CL members. The tranny shifting is crisp and as smooth as butter. Based on all the other local member reactions, we all agree our transmissions have never operated better.

The fluid is worth the price to me. Not only does it not need to be changed for 50k miles under severe driving conditions, it is also a pretty cheap performance mod.

You WILL feel the difference.