I have a leak on my NV5600, but that's been there since day one with the stock fluid. I ran that for 15k then started the RP intervals... My first oil change had some serious metal on the magnet, but since then very minimal. I attribute that to break-in. I think the stock fluid is ok if you change it frequently, I'm just happy with the smooth shifting with the synthetic. I'm going to push this next interval to 60k and see how things turn out.