99 6 Speed Clutch Noise When Lugging
Just picked up a 99 F-250 6 speed last night. Has 122,000 miles with a new clutch/pressure plate/etc. with less than 5,000 miles. I noticed that when you let out on the clutch with the motor at idle, you can hear something like a growling sound. This happens in first or reverse. If you give it a little fuel when letting the clutch out, there is no noise. With the trans in neutral, there is no noise letting the clutch out. Is this typical or any suggestions what to check.
Also, I'm going to be servicing the truck and wondering if it would hurt to switch the trans fluid over to synthetic. I've always ran Royal Purple in other transmssions and wondering if this is recommended.