OldLs400

I have a 98 LS400, 195k miles, and I'm not sure if any previous owner touched the transmission.

Right now the tranny works great, nothing wrong with it as far as I can tell. It does take a second or two to shift from, say, Park to Reverse, or Reverse to Drive, but it's nothing excessive. It's just a noticeable but brief pause before I can feel the engagement. This is normal, right?

Anyway, I've been reading about draining a bit by dropping the pan and adding a bit of fresh fluid. I've seen a few people say that it's been working out for them. However, has anyone had any bad experiences doing so? Did anyone's tranny conk out after a drain/fill? I don't want to fix what aint broke, but then, I don't want to skip preventative maintenance and cause more headaches in the future. I plan on keeping the vehicle for at least another 6 months or about 10,000 miles, but I'm all about it lasting longer than that.

Banshee365

I don’t have much experience with the A350. But, generally it’s a wishy washy idea to change fluid on a high miles unit especially if it is acting up any. Reason being is that the fluid will be contaminated but adds to the friction for the clutches. Exchanging the fluid with new clean fluid can cause a unit that’s barely hanging on to totally die. It’s good to change the fluid on newer units mainly to keep the enzymes fresh for the soft rubber seals and such to keep them playable. If your unit is original the soft parts have certainly hardened by now just by age. Changing the 2-3 qts in the pan typically won’t shock the system as fully exchanging the fluid would. On a totally healthy trans the engagement from neutral should be very quick. 2 seconds would be way too slow. I would be comfortable with 1 second or less for engagement. If I were you I would be comfortable draining the pan and refilling but not much more than that.

lexslexus

When I bought my '96, it had 175,000 miles on it and a small transmission pan gasket leak. I ended up replacing the gasket, fluid, and filter twice because the fluid was still seeping with new cork gasket that was put on the first time. Never had any problems with the transmission after changing everything out. Just make sure that the transmission pan is glued directly onto the transmission using Toyota Form-In-Place Gasket Maker. The only issue I had was extreme difficulty getting some of the bolts out and the glue on the pan did not want to budge.

BNastee

I've changed transmission fluid on two high mileage LS400s with no problem. **But**, I've had problems with other 90s front wheel drive Hondas and Toyotas after changing high mileage transmission fluid. To fix them (slow shifting, etc) I've used Lucas Transmsssion Fix fluid successfully.


Rich

aptoslexus

I've done it 3 times on my 98. No issues. You don't need to drop the pan unless you change the filter; there's a drain plug. That said, looking over the service records, it had had a drain and fill every 30,000 miles at the dealer. I'm at 129,000.

dicer

Most always there are no problems with draining and refilling automatic transmission fluid. Its the power flushes that can have bad results. Also using the one size fits all fluid that many places use will cause problems down the road.
And the one guy mentioned gluing on the pan? In the old days gasket sealer on anything on an automatic transmission was a no no, as it can break off and end up someplace its not wanted. And note it is super difficult to clean the gasket surface of the transmission case of the oil or fluid, for any silicon like gasket goo there can be absolutely zero oil on the surfaces it is suppose to seal, and said oil is constantly dripping from the transmission and running all over that surface, unless you turn the transmission upside down.

Losiracer2

Opposite to what people's though process on here....I had a transmission that would shudder when coming to a stop. So naturally I thought fresh fluid would solve it. I did one drain and fill and it didn't improve.

I found out it was my lockup solenoid, replaced that and it downshifted like there wasn't ever a problem.

So I opted to do some additional drain and fills and replaced the transmission filter on the last one.

Drain and fills are least impactful to the transmission and would help get the contaminants out in a more gentle process than a flush would.

I had 275k on my transmission when I did the solenoid and subsequent drain and fills. It now has 287k and I don't feel bad going WOT on highway on ramps with any fear of it being a higher mileage transmission. It shifts more reliably and crisply than it did when I first bought the car at 253k miles. So I believe that Drain and fills can only help prolong the life of your transmission. These 4sp Autos are pretty robust, A340E is what's in my 97'.

Amskeptic

It is actually the other way around. New fluid has the friction modifiers and old fluid gets too slippery as it is contaminated with metal slough-off. If you do a simple pan drain (2 qts) every once in a while, you gently replace the fluid incrementally without stirring up sediments that should be left alone. Those marketing promos to power flush are the kiss of death.
Colin