I don't known man, it might just be me being OCD but I bought a separate pump (and tubing) for each fluid.

About $10 each at Horrible Fright it wasn't a big deal. I only had to buy two though...one for the diff and one for the tranny.

 

I just wipe off the part that sticks down into the container. Then I pump a little of the new fluid into the oil recycling pan to flush out the inside.

 

Same here. I pump some of the fluid-of-the-day through the pump into a container before getting on with the job.

 

I pump out as much as I can. If time allows, I hang it in such a way to let any residual fluid drip out. I don't worry about whatever small residual amount is left inside the tubing and pump cylinder. IMO it's too small a volume to impact whatever new fluid you are pumping in.

Also consider there is residual old fluid left inside the gearbox, diff or t-case. That volume is likely much larger than any residual left inside the transfer pump.

 

Yah I actually thought of that.

I think what I'll do is I'll drain the old stuff out, then ill cycle the old fluid through the pump right back into the container again this way at least it will be residual old fluid that gets passed through with the same type of new fluid.

 

take it apart, clean with brake cleaner, reassemble, proceed with different fluid type.

 

I let it drain as much as possible, then I take it apart and wipe it out with a paper towel.