Hi, this is my first post on this board. I've lurked around a little and knew of the forum for years, though. My mother has a 2006 Ford Five Hundred with a CVT. She got the car at right about 60,000 miles, and it has 155K on it right now. She's never done anything with the CVT since we owned the car. It seems like everything is still currently fine, there was what we thought was weird shifting at launch, but we narrowed that down to the top engine mount connected to the front strut bar, at least we're 90% likely it's that. I believe it was getting caught in the mount, it's been better since I opened the inside of the mount somewhat. (Was going to change it, realized I needed a press and it couldn't be hammered out...) So other than that, no problems with the transmission with whatever is in there, and honestly it was never even checked. I told her at about 100K to try to get it flushed or drained, and told her to try to ask about it under warranty (she got a warranty that apparently only covered oil changes... ) but nothing happened. She only got scared a bit with the engine mount situation above happening about 10-15K miles ago. When I called a transmission shop, they basically told me they wanted nothing to do with flushing it. So anyway, it's possible the fluid in the car is factory fill, but it's possible the dealer did change it when they got the car. I believe the interval is 60K miles. It did have new spark plugs, it's supposed to come with platinums, and came with conventionals she ran until about 3000 miles ago (also wanted her to do those at 100K, but nope, only would do it when it misfired...) so I'm guessing the dealer put conventional ones in when they got the car. But either way, the fluid has either 155K or 100K on it, and seems to be doing fine. I'm just worried about changing it, but ironically I've had nothing but good luck changing fluid in normal Dexron III vehicles. No issues whatsoever with fluid changes. There is the theory that old fluid with the clutch dust will run better, but on CVTs that's not a factor, right? So should I just change it? The other obstacle is cost, too. On my Dexron III vehicles, I could use Supertech Wal-Mart ATF that was about $10-12 a gallon jug at the time. The official Ford CVT fluid is about $12 a quart, and it's 10 quart total fill, and I think a 5 quart drain? I was thinking, thanks to this forum and knowing more about specs, using Valvoline CVT fluid, as it's about $7-8 per quart and meets the specific Ford spec, and so far Castrol and other brands don't seem to explicitly state that it meets it. So I'd like to know, is there any danger in changing high mileage CVT fluid?