Jubane

Its about time for me to change the transmission oil on my RX. I was thinking of changing it to something better than the Toyota-IV to AMSOIL ATF http://www.amsoil.com/storefront/atf.aspx . My question is that once I drain the fluid there is a little more than a quart still inside the transmission. Would having both oils mix cause any problems???
Is there anyone else using the AMSOIL AFT fluid and does it offer better performance or atleast better durability than the Type-IV???
Is there anyway to remove the extra fluid in the tranny???

TunedRX300

Many Lexus owners have used Amsoil, try to use search, it is a wonderful tool.
To get more ATF out of torque convertor, see step 13 on page 2
http://www.amsoil.com/faqs/ATF_and_F...Procedures.pdf

mmahamm

People will do what they like. My personal preference would be to stick with what Toyota/Lexus recommends. If there are problems down the line, they are unlikely to provide any help if you used a different transmission fluid than what they recommend.

Fern

A Lexus tech once told me if you drain and fill the transmission with the recommended lexus fluid (my case is Toyota type IV) every 30,000 km (18000miles) the trani will last the life of the engine. That said, why would you want to risk using something else? Specifically since it is a known fact that other members experienced long term problems using fuid other than Toyota recommended.

Personally I prefer to play it safe, especially when the cost of a rebuilt trani is as high as it is.

ericok

Draining only removes about half the transmission fluid - not just "a quart" left behind.

TunedRX300

I agree, use Toyota T-IV only when you are still under powertrain warranty. It is more for your own ease of making warranty claim if your tranny fail. Which means you don't have to fight the service manager. Legally Lexus can not deny warranty claim according to federal Consumer Product Warranties law, often referred to as the Magnuson-Moss Warranty Act.

Under this federal statute, a manufacturer, who issues a warranty on your motor vehicle, is prohibited from requiring you to use a particular brand of air filter, oil filter, or other service or maintenance item, unless such item is provided, free of charge, under your warranty or unless the Federal Trade Commission (FTC) waives this prohibition against the manufacturer.

You have to make best choice after that. I have done search of Lexus owners of this forum who used Amsoil and so far I did not find one single tranny failure. There is one thread even disclosing a private conversation between an owner and Amsoil stating Toyota shared the chemical composition to Amsoil. Again make your own decision, stay with Toyota T-IV after warranty, knowing it does not handles RX's tranny overheating problem and perform up to Lexus' own recommendation (check ATF 60K under severe driving condition) or go with the more expensive Amsoil.
BTW, check this thread out, it turn out Toyota outsources T-IV to multiple suppliers, so mixing between brands is a non-issue if everyone has the same chemical composition
https://www.clublexus.com/forums/sho...d.php?t=194850

Jubane

Just to stay on the safe side I am going to stick with the Toyota Type-IV transmission oil. I would prefer to change all the transmission fluid and in order to do so seems that I am have to go with the power flush which my local Toyota dealer does and suggested. I have read alot that this is a bad idea and not to do it but nothing really substantial. If anyone HAS had something happen after a flush please POST.
Thankyou all for your advise

salimshah

Drain and fill, improves the % fresh quality of the fluid.

Power flush dislodges the particulates which may be moved around to clog up channel(s).

There is a safe method which does not use external pump, where fresh fluid is added as the old is pumped out by the trans. Does require proper care as the volume pumped out must be matched by volume added.

Agressive techniques usually make the matter worse.

Salim

ericok

Mobil ATF 3309 meets the Toyota Type IV spec. Not a synthetic. Don' t know if it's cheaper though. Amsoil meets it and a few other brands do also. If it meets Toyota's T-IV specification it's OK to use. Otherwise you should expect to get transmission shudder with non-compliant products (probably reduced life too). The Magnusen-Moss warranty act won't help you if you don't use a product meeting the manufacturer's spec.

TunedRX300

Again, search is a powerful tool, understand you are a newbie but did you try it?

thkim

It may be a matter of symantics here but Amsoil ATF is not Approved under Toyota T-IV. Their website states "recommended". They also outline recommended for Z1, T-IV, type F, Mercon V etc which are conflicting requirments. It's not possible to meet all these oils with one formulation. Check out any oil website and you'll see specific formulations for different ATF applications. The only after market product approved for Toyota T-IV is Mobil ATF 3309.

http://www.mobil.com/USA-English/Lub...l_ATF_3309.asp

Lexmex

There is definitely stuff (and even modifications) that I put in my RX300, including different grades/weights that are not approved by Toyota/Lexus, but I keep using them since I see benefit.

I still use Type-IV due to very strict importation requirements and lack of an Amsoil dealer down here (that could help), but it comes down to as TunedRX300 and I have done along with others, personal preference, testing of said fluid and seeing if there are any issues. In addition, a lot of us are out of warranty.

TunedRX300

Mobil also use the word "recommend" for ATF 3309, direct quote from the link your provided

thkim

Look down on the chart under "Specifications and approvals".

TunedRX300

I think we are spliting hairs with words here. "Recommends and Approved" is OK, "Recommends" and then list T-IV is not. While RX300's owner manual states "Use Only Toyota Genuine ATF Type T-IV " so no aftermarket ATF is approved.
Mobil makes good products and I use their Mobil 1 5w20 engine oil and 75w90 gear oil. But I would like to see scientific evident before stressing out on the wordings here.
Amsoil ATF's viscosity at 40ēC is 37.4, Mobil 3309 ATF is 35, mere 2.4 difference but no one really starts the car at 40ēC. At 100ēC, Mobil and Amsoil have same viscosity number.
http://www.amsoil.com/StoreFront/atf.aspx
Again, it is individual's preference. But I found those who had a tranny failure tends to be more willing to try another fluid as long as it is T-IV complying.
Anyone with Toyota T-IV spec, please post so we can compare.