This may have been posted, but I thought I would take a crack and see if I had anyone out there who can give me a solid answer. I am changing the PTU fluid in my new to me 2011 Ford Edge. For those not familiar this is a huge engineering error. They shrouded the AWD PTU in heat (exhaust, Catalytic, transmission) then didn't put a drain plug in and called the minimal fluid "good for life" with the only access is an inaccessible fill plug. So from what I have researched the way to handel this is try and get the fill plug off and use a suction device to get the old 75W140 out and replace it. Since this is the first time I have done it, and I have not cracked the fill plug, I am praying that it is just really black, and not loaded with sludge. Here is my question. If I get lucky, and I can get most of the fluid out, I want to change it, run it for about 1000 miles, and change it again with a VERY GOOD 75W140. I have limited time on things, but I was wondering what the best 75w140 gear oil is that can withstand the highest temperatures. I have heard Redline Heavy Shockproof is good, Any thoughts on Royal Purple (this one I can find pretty easily), or any other synthetic? I hope Im not opening a can of worms, but its a small amount of fluid (18 oz max) and I need some advice. Thanks