qha_vn

although I have already modded a radiator for the transmission hopefully for longer life of it at lower oil temp, would like to have your comments about this yes/no? why?

btw, i drive about 50km a day in a crowded city with average speed of 20kmh my tranny failed 2 times and just got it rebuilt completely (and added radiator)

will take some pix later at where/how the radiator hang

dicer

It gets a lot of constant shifting doing that. And its probably hot weather too. I suppose a trans cooler would help, I don't really know a good place to put it though. Are you using Toyota fluid in the transmission?

timmy0tool

iTrader: (7)

are you talking about a separate transmission cooler from the one that is already part of the factory radiator? the factory unit should be enough to handle stop and go traffic. what year is your car?

and yes always use toyota type-IV transmission fluid!

qha_vn

Toyota fluid isnt easy to reach here, i use castrol instead. will post a picture of where it is installed. its a secret now

qha_vn

yes, additional radiator. fluid flows thru factory one and then the new one. the new one alone can do the job well as newer cars have separate radiator.

its 1990

dicer

No Toyota fluid, means no transmission lasting long.

PureDrifter

iTrader: (10)

Any JWS 3309 spec fluid would work just fine. Toyota T-IV is the easiest/cheapest to get in the states but that is likely not the case elsewhere.

Mobil formulated the fluid originally for Aisin-Warner, but it is sold under the Toyota, Ford, GM, Volvo, Mazda, Nissan, and several other brands. Castrol also makes a 3309 spec fluid.

That said, a straight 3309 spec fluid is a better fit than a "universal" transmission fluid that lists compatibility with T-IV/JWS-3309 specification.



http://www.mobil.com/USA-English/Lub..._ATF_3309.aspx

qha_vn

thanks guys, but this topic wasnt mean for fluid type. question was yes or no and why

PureDrifter

iTrader: (10)

yes, works great, the GS400/430 as well as SC400 guys have been adding them for years to decrease trans fluid temperatures.

qha_vn

great to hear. thanks PureDrifter

dicer

What are the temperatures in your area? Does the car have lots of weight in it? Are there a lot of hills to go up?
Is the car used as a work car like a taxi? And when it comes to Lexus transmission problems the fluid does play a huge role in it. Just search the forums, it is the number one cause of transmission failures using the wrong stuff. Spec numbers or not. Now if your transmission was rebuilt with non Toyota parts that is friction material and rubber parts, and the torque converter is new or reman, then you could use the aftermarket transmission fluid that is close to spec. just remember the shift calibrations are for a certain fluid with its friction modifiers, so either shift feel or shift slipping can end up wearing the parts faster. I do not think it is a good idea to mix fluids.
The friction materials in the transmission have the fluid soaked into them, putting some other fluid in could cause some kind of reaction or modify the friction in an unknown manner.

PureDrifter

iTrader: (10)

actually the number one cause of automatic trans issues in the LS or any other is overheating the fluid,

The fluid is an issue but not the issue OP is trying to address by adding a transmission cooler.

djamps

+1 on a cooler. The extra 1qt or so capacity helps too. I'm a fan of oil coolers too.

qha_vn

temp is high all year round (about 30-40 degree C average). no additional weight, no uphill, no like taxi. biggest issue i think is the stop and go traffic at 20 km/h average daily, home to work & back. stop and go creates a lot of heat from tranny while not enough air flow as the car is slow

again, i add a cooler to lower tranny temp (like many other newer car do)

djamps

Might want to add a fan on it if there is a lack of airflow. Radiator with no air flow doesn't help much.