Places that sell tranny flush kits ( like IPD) post a disclamer that on very rare occasions, flushing an old, worn out tranny may cause post flush problems. This comes from the theory that some really trashed trannys with destroyed internal clutches may actually use the clutch materal suspended within the ATF as friction to move the car. Flushing this clutch debris out with a fluid change would remove the friction medium that the tranny needs to move the car. This senario would be VERY rare. I'm sure it's a CYA statement. I'd flush that baby with syn fluid if you can swing the extra $$.

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