100K Mile Transmission - Fluid Change or Not

[superfast48]

Thanks for the input. I heard that if the fluid has never been changed, that "changing" it would be a high risk for problems immediately following.

[carguy07]

This is just my opinion, but I think the issue was along the lines of a high mileage tranny that was failing would be pushed over the edge if the fluid was changed because all the extra metal and junk in the fluid would keep it from slipping (gave it the extra friction needed to work). Also the viscosity of the old fluid was real thick and the new fluid would increase the line pressure and potentially kill it off.

If your tranny is healthy I would change it out and drain and fill until it’s clean. If it’s slipping and dyeing I would not touch it. I always felt that the don’t touch high mileage fluid thing was more of an old american car issue (nothing to back that up just my opinion).