fluid change on replacing an auto-transaxle

[lee]

Anybody want to offer their opinion of how I should go about fluid/filter changes when putting in a junkyard transaxle?

As to why I'm doing this a) 125k miles on the old one and the brake band is going, and b) I'm going to a different final gear ratio (from 3.545 to 4.111) to save a little stress and gain a bit of pep off the line.

The new (to me) transaxle (Subaru) has 29k miles on it. I have been thinking I would drop the pan, put in a new filter, run some cheap (super tech?) dino fluid in it, maybe with some Auto-Rx, for a few miles, then pull the pan again, filter check/change before going to a synthetic.

suggestions/alternatives???

 

[Farticus]

29000 miles isn't bad for a junkyard tranny, fluid might still be good in it, but for peace of mind I'd go with what you had in mind.

 

[XS650]

quote:

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Originally posted by Farticus:
29000 miles isn't bad for a junkyard tranny, fluid might still be good in it, but for peace of mind I'd go with what you had in mind.

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I agree it should be changed. And a UOA on the old oil would give an indication of the condition of the tranmission.

 

[lee]

thanks.

Can't do a UOA, all the fluid was drained (including the differential) before it was shipped to my local yard (trucking rules I guess).

 

[XS650]

quote:

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Originally posted by lee:
thanks.

Can't do a UOA, all the fluid was drained (including the differential) before it was shipped to my local yard (trucking rules I guess).

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That does simplify the decision process

Actually, I see the problem was my reading comprehension.... Running a change of fluid through before you put your final fluid in seems like a good idea. In that case, a UOA on oil just run a few miles would be of questionable value.

 

[Matt_S]

Your plan sounds good to me. The only think I would add is a third fluid change with your final fluid, given that you only get about 50% of the fluid out on most transmissions. That'll give you a higher percentage (about 75%) of the good fluid.

 

[lee]

thanks, I had planned on another change, just didn't say so. My car drains out about 7 qts with a simple pull the plug drain, which is 70% (holds 10 when the torque converter is considered, unfortunately no drain for it). So the second drain & fill of the final fluid should give me slightly over 90% change.