I wanted to start a conversation about the transmission fluid change interval for Toyota and Lexus's transmissions having lifetime fluid. Please respond with facts or documentation not what a 22-year-old Lexus master mechanic tells you.

1. First of all, Lexus does not make their transmissions Aisin Warner does.

https://en.wikipedia.org/wiki/List_of_Aisin_transmissions

2. Aisin Warner recommends changing the transmission fluid every 2 years 20000 km in Japan where the transmissions are built. (See pdf below)... Aisin makes their own fluid for their transmissions

http://www.aisinaftermarket.jp/en/products/atf/
http://www.aisinaftermarket.jp/en/pr..._CFEx_AFW+.pdf



3. Aisin USA markets the WS fluid in the USA site without the mention of fluid change on the US site. Lexus markets same transmissions as having lifetime fluid. I hear a lot of people on here talking about Lexus transmission only take Toyota WS fluid would you trust Aisin WS fluid?

https://aisinaftermarket.com/english/products/23.html

https://aisinaftermarket.com/uploads...ochureComp.pdf



4. While Lexus dealerships where I live are saying to never change your transmission fluid Toyota dealerships in the same area are changing it every 36,000. Miles https://www.joemyerstoyota.com/servi...houston-tx.htm



5. I changed my fluid Drain and fill the same amount and the old fluid looks like garbage. Wil do it again when I change the oil again.

 

Aisin is 30% owned by Toyota, according to Wikipedia.

I have done 8 drain and fills on my Aisin 6 speed using Mag One Full Synthetic Low Viscosity Multi Vehicle ATF which claims WS compatibility and at over 70,000 miles my RX350 shifts better than when I bought it.

https://mag1.com/products/transmissi...mission-fluid/

 

It's worth dropping the pan, if only to clean the magnets. Keep them clean and they're in a better state to keep particles out of the box that make it through the filter.

 

Does this apply to my fourth generation Lexus IS 250 which is rear wheel drive? I have gone some 40k miles now with no transmission fluid change.

 

If you drop the pan and change the filter without changing all of the fluid out then the dirty fluid will get back into the filter. I say do drain and fills until the fluid is red again then change the filter it is like running dirty water through a new water filter makes no sense.

 

This applies to all Lexus vehicles. The WS fluid is not even synthetic.

 

You can use almost any ATF fluid you want without an issue.

The key is to keep the magnets and filter strainer clean.

Refer to this link for more info. It'shttps://www.clublexus.com/forums/car-chat/935914-aisin-mazda-6-speed-auto-pan-filter-change.html
its a FW6A-EL made by Aisin. Very similar unit as used in Lexus Tranverse FWD applications.

 

This is all good info

 

This is helpful also

 

i have same questions
https://www.mazda3revolution.com/thr...m-heat.243817/

 

Wondering myself. Opinions on whether this should even be done seem to vary a lot, both from mechanics, owners, etc. I am no Lexus mechanic, but generally it seems to me over time eventually tranny fluid will break down like any other fluid...other than cost, why would you NOT change it out?