PTU report: I sucked out 75% or so of the PTU fluid in the wifes '14 SEL and replaced it with Amsoil last weekend. I used the same tube to fill it as I did to suck it out so when I added to the PTU the tube was low in the PTU and I pumped in 6-8 ounces or so extra and let it come out of the drain plug hole. So, I'm hoping it's mostly Amsoil now. I'll do it again in a few thousand miles. Small build up of stuff on the drain plug magnet. Hers at 59,000 miles looked much better than mine did at 42,000 miles. I had to add to mine and drive it around my yard just to be able to suck the crap out. Her's at least flowed when it was warm and was able to be sucked out. BTW, a 3.5 L SEL is harder to do than a SHO because of the cat location so we have that going for us at least.
