Well, I just picked up my truck from the Dodge dealer after its 30K mile service. The largest part of the bill was $188 for 7 quarts of synthetic gear lubricant! What a rip-off! The dealer insisted that I needed synthetic lubricant, and I checked and that is what my owner's manual says. In fact, my truck was supposed to come new with synthetic (I have the tow package). BUT the same dealer also changed my gear lubricant at 15K miles, and only charged me $3. 50 a quart. Do you suppose he drained my synthetic lubricant and replaced it with dino lubricant? I will know better next time, I am going straight to Amsoil. BTW, what interval is recommended for changing the axle lubricant when you use synthetic? I can find nothing other than 15K miles with Schedule B maintenance.