thought it worthwhile to add to this post rather than starting a new one. I have a 05 Land Rover Discovery 3. Currently Im running Penrite Pro Gear 75W-90 GL-5 diff oil. The front diff in particular dosent hold much oil - .9L. Summer is just ending here, but ambient temps can be very hot - around 40-45degC, winter is nice with around 25degC days the norm. Due to being remote the disco does alot of highway miles and often has a camper trailer (around 1200kg) behind it. My last lot of UOA from the diffs show a high iron content after around 50,000km on the oil. Im thinking of changing from the current oil to something better to see if it reduces the iron content, and possibly bumping up the viscosity to a 75W-140. Any recommendations?