Took my car for oil change and guy told me transmission fluid is black and I need to have it changed. I know sometimes when you do change the fluid that the transmission could go bad. My car is a '93 Sc300 with 134k on it. What do you guys think? Change it or leave it be?

 

No, when you run crappy black fluid full of metal, tearing up your seals THEN it will fail.

Have it flushed.

Muscle car guys, I swear. I have heard this too.

 

The tranny fluid should NEVER be black. Flush it. NOW!

 

I wouldn't flush it, just drain and refill. Do it a couple times with driving intervals in between.

 

Don't flush it'll be too harsh on the transmission, just as Luxor mention, drain and fill. Then next oil change do it again if you like.

 

Im sure this sounds stupid but whats the difference between draining and flushing..? Doesnt new fluid get put in either way?

 

There's only 4 quarts in your tranny oil pan, the rest of the 10 something quarts is in the system.

 

My mechanic tells me he flushes when he change the oil so no particles are stuck in the lines. He says draining and refilling is basically a half assed job what do u guys think?

 

Is it true that only factory oil should be used when changing the transmission oil?

 

Well see, the reasoning behind doing the drain and fill, is because all that nasty stuff builds up on the seals off the trans and other parts. If you flush and put nice clean fluid with really good cleaning properties in it, it will clean all that stuff up, and your trans might leak and all sorts of things. I am tired so forgive the beginner explaniation.

 

If you dont flush it, the crap in the system/leftover dirty fluid will mix with the clean fluid

 

Its a double edged sword flushing it, Yes you will probably get improved function BUT if you flush it depending on how long the tranny has been neglected most likely all the gunk and stuff has found its place in your tranny.
When you got 20 year old gaskets covered in metal, burnt fluid, pieces of clutches etc it somewhat "holds them in place" If you flush it most likely it will remove whatever is holding all your seals and what not together.

Im always conflicted when i get a neglected tranny in a used car buy, sometimes i just bite the bullet cross my fingers and flush it but on my first sc300 i wasnt that brave and just slowly cycled all the crap out. putting in a new filter ever 2 or 3 drain and fills.

Safest thing to do is drop the pan, fill accordingly and repeat again in a few weeks. Even though its just a chance you could fck your tranny up by flushing it why take that chance???

 

you do realize there is magnets in the bottom of your pan right??? The metal isnt going anywhere but the bottom o the pan. import guys....

 

I love your comment. Can't really blame them, it's the way their trannies are built.

I know now why these domestic car lovers always think the tranny will more likely go bad if you do a flush. I found myself working on my uncle's '99 Isuzu Trooper the other week, my uncle have never done any kind of maintenance to it at all ever since he got the truck. He just refills the engine oil from that crank case whenever it's low! Now, he started feeling harsh shifts from the tranny lately that gave him the idea of doing a flush. The first mechanic messed up for sure, because after 2 weeks of usage, it wouldn't shift anymore to 2nd gear or higher and he didn't do a proper refill of oil so it was very low on oil by the time I worked on it.

When I got to work on it I found out that it was a sealed type tranny, meaning no dipstick or anyway to check the tranny fluid. So I did a lot of research and it turns out that the tranny used for it, the 4L30E, was shared by GM, Isuzu & BMW, and it had a lot of major problems!!! The reason for it being sealed type was because it was a 4x4 tranny, meaning GM designed it to last a 100k miles without maintenance, until it just breaks down, which eventually is what happened to my uncle's Trooper. So now, the car is still in great condition, but he's looking at needing to get the tranny rebuilt for around $1800-$2400!!! Now, tell me if its worth it?

Thank god for imports!!!

 

It is true that flushing a severely neglected auto can cause it to fail or slip badly. Even so, I would still take a shot at it and see what happens