I like to get some opions on this matter.I have been switching the oil in my ranger over to synthelic the ares I have left are the tranny and the transfer case.I have these qustions on the tranny when I change the oil before I use the good oil first do I put some walmart oil in to flush all the old away then change to the new synthelic? and does the transfer case have a fill line? or is it like a diff when it run out its ok.