Hello all, new here although not new to forums. I recently picked up a 1995 LS400. My questions is this:

I'm sure everyone has heard someone say "if its been a long time, don't flush or change your transmission fluid because the new fluid could cause slipping/issues. It does make some sense because the millions of tiny holes that are under pressure are used to having this fluid in them. However, I want to get the maximum life from the transmission. When I got the car it clunked reasonably hard when putting it into drive or reverse. I checked the dipstick, and it was way overfilled (previous owner). I then drained out about a quart and a 1/2 to 2 quarts and now it's in the correct operating range. It now hardly clunks when going into drive or reverse which is great. However, the fluid didn't look all that healthy and was pretty dark.

So here lies my concern: do i just drain out as much as I can and replace it with new fluid? Surely the new fluid will mix with some of the old fluid. OR do I do a proper flush at a shop to get out all of the old fluid but risk damaging the components from the pressure of the flush as well as potentially accelerating the end of it's life from potential slippage.

Thanks for all of your input, I absolutely love this car, they don't make em' like this anymore.

 

Welcome to Club Lexus.

This thread will be of interest:
https://www.clublexus.com/forums/ls-...er-thread.html

 

I've read lot's of opinions on this subject here. I understand why you'd want to change the fluid. Because of the high mileage and possibility of all sorts of crap in suspension, the safest bet I've read is to do a partial drain and fill. Then use the car for a "while" and repeat the partial drain and fill. The idea is to gradually dilute the old fluid with new fluid over time. Some have suggested doing this 3-4 times until the fluid looks much better. Not scientific or specific, but it makes sense from a careful/gentle point of view.

 

Sweet, yea makes a lot of sense. I've read several people on here doing this after reading a couple pages of the sticky. I appreciate the reply! Once you drain out the pan, which is 2 quarts? Then you just refill with 2 quarts I assume?

 

I'd like to add to this:

If, while doing this, you notice it start slipping while you're doing this process, that confirms that the transmission fluid is providing the final little bit of necessary friction necessary to keep the trans alive. You should stop replacing fluid at this point and start saving up for a rebuild.

 

Perfect, thanks for the guidance. Any places to recommend in the southern part of the US? I'm in Arkansas

 

Flush machines do what they say they force high pressure cleaning solvents back through the transmission and clean out some of the accumulated junk that has formed. There are small passages and galleries through which oil or automatic transmission fluid flow and there are one-way valves that keep the fluids from backtracking for whatever reason. By using an aggressive cleaning procedure like flushing, large chunks of accumulated sludge are broken off and forced backwards through these galleries and valves and more often than not, lodge tightly and block them. This cuts off the normal flow of the fluid and causes lack of lubrication and abnormal or no shifting in a transmission. The results are expensive repairs more than likely.
The flushing procedure is usually fine on newer low mileage vehicles much of the time, but you are a brave soul if you flush it at this point. It's a roll of the dice.
There are staunch advocates out there that state you should never ever flush an auto-trans period, just drain and refill.
You decide.
Cheers !

 

I have done drain/fills on both my 97 and 98 LS's and it has only helped them. 220k on the 97 with its first drain/fill under my ownership at 172k. The first 2 fluid changes made a big difference on the low speed gear engagement and full throttle shifts. A drain will remove about 2 quarts, the trans holds a total of around 8 quarts. So just drain ~2 quarts, fill it back up, drive it a while and drain it again. Use only Toyota T-IV fluid, no generic crap. Also, make sure you are checking the fluid level of the trans while the engine is RUNNING. You want the fluid to be warm and fully circulated into the transmission torque converter, pump, and passageways. With the engine off, the fluid level will appear overfilled.

 

I would just take some tubing and one of those little fluid pumps and suck out like a quart of fluid through the filler opening... that way you can be exact with the measurements, only introduce a bit of new fluid at a time, and not risk making a big mess draining the pan

this way you can gradually introduce new fluid (type t-iv) and know exactly how much to put back in

 

PERFECT. Just keep the amount in and out exactly the same.

 

Here's my two cents: About 3 years ago I noticed a lurch going from Park to Drive, as well as shutter going from 45 to 55 mph. I adjusted the transmission line pressure cable near the throttle body to specification. Then, I basically disconnected the trans cooler line from the transmission to the radiator (the one that connects with the passenger side of the radiator) at the radiator and put it into a container. Then, with a funnel in the trans dipstick tube, I started the car in Park and started pouring trans fluid into the transmission as the the old fluid was being pumped out by the transmission. At idle the transmission will pump about 4 quarts in 30 seconds. As the fluid started changing color from dark brown to cherry red I stopped this process (about 8 quarts total). This was a simple, complete fluid replacement, not just a filter replace and fill. Note: this is not a "flush" because I did not force any fluid by any means. The transmission fluid pump did all of the fluid moving. The point, I replaced ALL of the old fluid with fresh 100% synthetic transmission fluid compatible with Aisin transmissions. Finally, with 100% fresh fluid in the transmission, then I did a "drop the pan and replace the filter" . I did this last because I did not want to contaminate a new filter with old fluid. Total fluid needed was about 12 quarts. So, 40,000 miles later I haven't had transmission issues. I perform a filter replacement once a year because I have a high mileage car (370,000 miles) and I over pamper the car. Good luck.

 

Glad that worked out for you. Sounds more efficient than multiple drains of 2 its per drain. But it is also a gamble according to many opinions out here, changing that large amount of fluid on a high mileage car that never had a fluid change. My 2016 es350 is coming up for 60K service and feel comfortable doing a full drain and refill because of low mileage/time.

 

With shutter, do you mean it felt like the gas was pressed/released quickly several times, like some sort of shaking? Because I have this problem but I read that it can be fixed by new ECU capacitors.

 

I wouldn't dare do a flush or drain/fill at this milage. Best bet is to drop the pan.

 

I did the partial change on my 97 about 7 months ago, put around 2000 miles on the car since . I didn't notice any difference in the transmission but it was fine before and I had it done because it seemed like the thing to do. The garage said the fluid in there looked like it had never been changed. The car had 190000 miles on it then. Just a jerk from P to D when the car first start but that could be the NSS apparently. I had it done at a garage so I kind of regret it. If you can do it yourself the partial change method is fine. But these cars are beasts. It was running with too much fluid for how long? Changing the fluid all at once, I don't think I have read anyone's comments in any thread about doing it and having issues. Just lots of owners saying it can be bad.