Anybody else using Royal Purple Synchromax? I had put Redline D4ATF in my 5 speed and it worked well. I just recently drained it and installed the Synchromax. At first I didn't see any difference, maybe even a little harder to shift, but after it had been in a week or so, it does seem like it might be a bit better, a little smoother shifting. My son has it in his '04 GT and he said he noticed an improvement - especially in hot weather. Just wondered how others felt about this product.