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Re: change tranny fluid ? Posted by Ari [Email] ![]() ![]() In Reply to: change tranny fluid ?, Kimo-saabi, Mon, 8 Jan 2001 22:23:46 Members do not see ads below this line. - Help Keep This Site Online - Signup |
You'll know the consensus after reading all the posts.
The automatic transmission in the 9000 is fragile, and the BEST thing you can do for it is to change the fluid regularly. The 9000 autobox is non-electronic, which means it uses transmission fluid as the working medium in a hydraulic computer, deciding when to shift. The valve body of a autobox is an amazing and terrible thing to see - a maze of little passages and holes, with springs and ball bearings moving around under differential hydraulic pressure. A little bit of dirt or sludge can bring it to its knees. And if the box starts shifting wrong, it can quickly destroy components.
Also, there are a lot of sliding components in the autobox that need lubrication. The lubrication of fluid decreases with age and temperature. The less lubrication, the more wear to components. The more wear to components, the more 'stuff' floating around in the fluid to (1) gum up the throttle body, and (2) abrade parts and wear them faster.
I recommend changing the tranny fluid every 15-20K miles. Changing the fluid only gets out about half of what's in the system, so some of that fluid is going to be around for 50 or 60K miles anyway. By changing the fluid, you take out wear causing particles floating in the fluid, take out corrosive chemicals caused in the fluid by heat, and take out fluid that isn't as good a lubricant as it was when new.
I can think of no good reason to leave the fluid in. If you do, you are guaranteed it will last the life of the tranny. Of course, that will be a short, brutal life.
I would stick with a good quality (I like Castrol, but that's just a personal bias) Dextron II or III fluid. There will be some argument about synthetics. Synthetics do provide excellent flow characteristics at low temp, more resistance to losing lubrication with time, and better heat resistance. For years Saab recommended against synthetics in autoboxes. Without saying which is right (because the argument is still open), I go with good quality non-synthetic. I change the fluid frequently enough that the good quality non-synthetic doesn't have time to break down. I don't live in harsh enough a climate to feel the extra temperature range of synthetic helps. And lastly, if Saab doesn't think I should use synthetic, who am I to argue?
If you do use synthetic, still replace it at 15-20K mile intervals. You want to flush those particles out!
Good luck!
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