2011 IS 350 F Sport Transmission Fluid Change AND Adding an External Tranny Cooler - Lexus IS Forum
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post #1 of 6 (permalink) Old 01-07-2017, 07:20 AM Thread Starter
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2011 IS 350 F Sport Transmission Fluid Change AND Adding an External Tranny Cooler

I have owned my 2011 IS 350 RWD F Sport since brand new and the car only has 10,800 miles on it but all of my automatic transmission cars that I have ever owned over the last 35 years have always had an external cooler added by me-I have never had a transmission failure. I currently have 2 cars with coolers that I put on (actually 3 cars): 1994 Mustang GT Convertible (2 Long/Dana Double stack coolers (42,000 GVW rating) in the grill doing all the tranny cooling (no radiator cooling) and 2008 Chrysler 300 with 1 Long/Dana Double stack cooler (24,000 GVW rating) in conjunction with the factory air cooled trans cooler in the AC condenser. Needless to say I probably have much more mechanical ability than the typical lexus owner (I removed and reinstalled recently the L-82 V8 engine after a complete rebuild by me in my 78 corvette) and have been researching how to change the fluid in the "sealed" (there is NO such thing as a sealed for life tranny fluid-that is called planned obsolescense) A760E Lexus tranny for some time and how to add an external cooler in the grill to cool the tranny fluid....both tasks have been very difficult to solve up to now.

So here is what I have discovered after hours of research on these issues:

My 2011 Lexus IS350 RWD uses an Aisin A760E transmission and I believe is the same one used in all RWD IS250/350's from 2006-2013(not 100% sure all years are the same but most probable). This same transmission is also used by Toyota in the 2011/12 Tundra/Sequioa. All these transmissions whether 2/4wd use an ATF warmer on the side of the tranny externally fed by coolant from the engine to heat the fluid quickly and help to keep the trans fluid from overheating (very poor design). This point is important later about changing the fluid every 25-30K miles for maximum transmission life expectancy. The reason for adding the tranny cooler is to avoid transmission failure after 100,000 miles and to facilitate a transmission change...not for racing.

A couple of other differences between the is350 Aisin 760E or H and the tundra/sequoia...the full tranny capacity of the Lexus version is only 8.X qts versus the Tundra/Sequioa 11.X mainly due to the fact that Lexus uses a smaller transmission pan (1.5 qts) versus the tundra's 3-4 QTs AND a drain plug....this difference will shortening tranny life further..not good.

The Lexus A760E/H and the tundra/sequoia all use the same external ATF warmer as long as the trucks do NOT have the towing package. For tundra/Sequioa's with the TOWING package the spacer that the ATF warmer attaches to on the lexus is replaced with a spacer/trans oil thermostat with an out and an in line going to an external cooler in the grill. I have located the Toyota part number for this oil trans spacer/thermostat for the tundra/sequoia towing package and will report back when the install is completed in a few months. Of course, Toyota sets this thermostat to open when trans fluid exceeds 200+ degrees which is way too hot. Trans fluid should ideally run about 140 degrees for maximum transmission life. The easy way around the thermostat is to leave the pin in the plunger as it comes from Toyota to correctly add tranny fluid to the externally cooler and to replace the pin with a stainless steel cotter pin to keep the fluid running to the cooler at all times. I will probably later by pass the coolant to the ATF warmer since all my cars always use air cooled coolers only and I have never had an issue. I may also replace the tranny pan with a tundra's for extra capacity. Clearly lexus did not design this tranny for long life.

Once the cooler is installed, I can remove one of the lines from the cooler to remove 1 gallon of fluid, add a fresh gallon back into the tranny (yes I know there is a procedure for this), doing it twice along with the trans filter and you have fresh tranny fluid for the A760E AND it will run much cooler. Yes, I am well aware of cooler tranny fluid implications (all good BTW) and my daughters 2001 Pontiac Grand prix with the crap 4T65E FWD tranny with 2 external coolers driven year round in sub freezing weather is almost at 200,000 miles on this tranny.

Hopefully some others are interested in this post............

Last edited by Jbamonte; 01-07-2017 at 07:28 AM.
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post #2 of 6 (permalink) Old 01-07-2017, 09:26 AM Thread Starter
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If anyone views this post as useful or wants to hear more info, please respond as such or I will just let it die since I don't want to detail my conversion and addition of the external Tranny cooler if no one is interested. Thanks
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post #3 of 6 (permalink) Old 01-15-2017, 10:22 AM
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Originally Posted by Jbamonte View Post
If anyone views this post as useful or wants to hear more info, please respond as such or I will just let it die since I don't want to detail my conversion and addition of the external Tranny cooler if no one is interested. Thanks
Of course we are interested. You just need to understand that there is a small group of people like yourself that actually are interested in working on their cars etc. The rest are ricers that care more about LED headlights and body kits or rims and tires for their IS250.

So yes please document (pictures) and post the procedure you went through. This board is a little quiet but there is another board that seems to get a lot more traffic. Most folks cross post between both boards.

Thanks....
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post #4 of 6 (permalink) Old 01-15-2017, 06:20 PM Thread Starter
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Originally Posted by Mrfixit View Post
Of course we are interested. You just need to understand that there is a small group of people like yourself that actually are interested in working on their cars etc. The rest are ricers that care more about LED headlights and body kits or rims and tires for their IS250.

So yes please document (pictures) and post the procedure you went through. This board is a little quiet but there is another board that seems to get a lot more traffic. Most folks cross post between both boards.

Thanks....
I will post the whole procedure when it is completed but it may be a bit since I am still working on the best solution but closing in...it is going to happen. I will also check out the other forum which I know of as well. Thanks
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post #5 of 6 (permalink) Old 03-18-2017, 11:14 PM
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Pics

Hello,
Did you ever install your Tranny cooler and take pics. I just purchased a 2006 IS350 sport and love it. I will be doing about 7 or so autocross events a year as well as using it as my daily driver. I'm a nooby so any and all advice is appreciated.
Thank You for your time
Barry
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post #6 of 6 (permalink) Old 06-20-2017, 09:43 PM
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Quote:
Originally Posted by Jbamonte View Post
If anyone views this post as useful or wants to hear more info, please respond as such or I will just let it die since I don't want to detail my conversion and addition of the external Tranny cooler if no one is interested. Thanks
Of course we are interested. You just need to understand that there is a small group of people like yourself that actually are interested in working on their cars etc. The rest are ricers that care more about LED headlights and body kits or rims and tires for their IS250.

So yes please document (pictures) and post the procedure you went through. This board is a little quiet but there is another board that seems to get a lot more traffic. Most folks cross post between both boards.

Thanks....
Im no "ricer" per say but i do like lexus factory rims(given they are newer rims that did not come on my make/model) and led headlights. I bet everyone in here would prefer a more efficient vehicle. i too am thinking about installing an external oil cooler as well as adding performance ams atf oil or similar. researching here i have not found anyone who is using that oil or anything about atf oil changing. Im not using my car for racing. its my daily driver but some performance oils are made to take more abuse than some factory oils. I do floor it quite often lots of on ramps lots of short bursts of full throttle .But i have an 01 with almost 170k miles. Im just afraid its gonna take a crap on me after i change the oil. Has happened to me on other vehicles as well.
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