Jay1

I bought a 96 toyota 4runner with 187,000 miles and i want to flush the trans fluid but im not sure if it will cause problems. i dont have any history of it. The fluid is a little bit dark. what do you guys think should i get it flushed or not.

Leviticus6432

I worked for a performance transmission shop for years... We didn't recommend changing the fluid for the first time if the transmission had over 120k miles on it. If it has been changed periodically its whole life than its fine to change it. But if not than it can cause some big problems if you change it now.

Leviticus6432

basically you need to figure out the history or leave it alone, i'd say

fork

why is that? and why 120k? mine wasn't changed for over 100k and I changed it, and had zero problems from changing it to the prescribed fluid. idgi.. none of my manuals have ever mentioned this, but i've heard it before. someone educate me

Jay1

I been thinking about swaping it out for a manual trans. My tacoma with a manual trans seemed like it had more power.

Leviticus6432

Well over the life of an automatic transmission, the friction material on the clutches slowly wears off. This material then just floats around in the transmission fluid. This makes the fluid... less slippery. After around 120k miles (it does differ between transmissions, but there is not really a set number) the automatic transmissions are at a point where (usually) more than half of the friction material is just floating around in the transmission fluid. However, the clutches still work properly without slipping because the fluid helps make up for the lost friction. If you change fluid at this point you are getting rid of the majority of your friction material and there is a good chance that the clutches will start slipping. Once the clutches start to slip it isn't long until the transmission is shot. Another theoretical issue is that the friction material in the transmission fluid thickens the fluid as well and helps prevent internal leaks. Seals wear over time, and putting new, thinner fluid in the transmission could start a whole slew of new issues.

Leviticus6432

Automatic transmissions almost always have more power loss than manuals, its because of the torque converters. You are also going to feel like you have more power when you can use the clutch to take off and shift more agressive. Most automatic transmissions are "programmed" to shift very gently from the factory. This makes the drivetrain feel less powerfull in my opinion.

fork

oh. learn something new every day i love YT
regarding shifting, the cable on my a340-whatever it was had a cable going to the butterfly valve to control that. the housing for the cable burned on the header and the result was that the cable would stick in the pulled position, which occasionally made shifts brutal. but it definitely would shift hard when I needed it to because of that. if I still owned the vehicle it would be kind of cool to run that into the cab and control it via lever

Leviticus6432

If it makes you feel any better Jay, I have a 97 lexus ls400 and the transmission is nearly identical to your 4runner's transmission, and it has 245k on it and I've had no problems with it. Its one of those things, if it works, leave it alone. Just be ready when it goes lol. On the other hand, if you want more of an agressive feel from your auto, there is a company that makes a replacement valvebody for it that is supposed to add some kick to the shifts. I'd recommend rebuilding the tranny before tryin to mess with that though.

Leviticus6432

fork, i would assume that would be very hard on the transmission, depends on what exactly it controlled... I'm not that familier with it honestly. What is the butterfly valve?

fork

the throttle valve inside the throttle body, which is opened by the throttle cable. yea it couldn't have been good for the transmission at all. the person i traded it to fixed that pretty quickly. i didnt mind it so much but i had no intention of keeping it very long

GreenArrow19

Don't mean to hijack the thread here but that seems to explain what is happening to my tranny. I got it with 136k and flush the fluid and now, at 150K, I am starting to feel it slip alittle. If your a bone-head like me who had no idea about this information, is there anything that can be done? Rebuild it?

Leviticus6432

Well our shop would prob recommend running one of the top of the line oils... they used Royal Purple. If you spent a bunch on good fluid and maybe added like a lucas oil addative (i think they have a stop slip one) It might prolong your tranny's life a little. I personally would just look around on craigslist or somewhere for a low mileage trans to swap in... or like Jay maybe switch to an manual. You could have yours rebuilt when it goes but you'd have to find a shop comfortable with it. If you wanted you could just add some Lucas to your fluid, but I've never been a believer of "miracle" working addatives. Its sad and pricey, but there really isn't a way around fixing it unless you get rid of the vehicle. But just remember, clutches are clutches so with that in mind, throwing away a vehicle because the auto trans went out is just like throwing away a vehicle because the manual transmission's clutch went out. Its just a little more pricey to fix the auto.

Leviticus6432

Greenarrow... Just read your other post. Ya there's no way your trans is gonna live for 150k more miles if its slipping now. I'd look into fixing it while working on everything else. You might be able to rebuild it yourself if you have the shop for it. It would prob be around 500 bucks for all the stuff you'd need.