the lx has approx ~100k miles. lately i've noticed that there has been a clunk during decelleration of about 3miles/sec at exactly the 15mph tick mark on the odo. this clunking does not happen all the time and i believe this occurs during the downshift from 2nd to 1st gear. i checked the archives and couldn't find much on my situation. i drove around for 15mins, put it through L, 2, D, N, R, then P and checked the auto-tranny fluid. it seems low. it's on the border line of cold when it should be on hot/warm. is a 15mins casual drive around the block enough to warm up the tranny fluid to give me an accurate reading on the dip stick? approx how many qts should i purchase and what brand should i use (other than OEM) if it is on the "cold" mark? on another topic i'll be driving through some mud.- is it okay for me to make a u-turn or drive in reverse with the center diff locked? or should i unlock it?