I thought that I posted this the other day, but can't seem to locate it so I'll try again. I was preforming a first time service on this 2000 Mack CH613 tractor since it was transferred to My location 2 weeks prior to this scenario. Everything was as usual then I pulled the plug on the front drive axle to check the gear lube when a grey like substance came rushing out, I assume it was water that was mixed in with the gear lube, but it doesn't really feel like water contamination it was extremely overfilled. The day before this complete service LOF etc. I installed a new torque arm on that axle, towards the end of the day thought I heard some "Howling" from the rear end. Sorry to jump around here I drained the rear end over Sunday and on Monday decided to pull the axles and remove the top loader from axle that's when I noticed 2 of the top loader bolts were loose and that the silicone gasket was damaged. Could this be where the "water" came from? While we were removing this top loader the aluminum side cover (the one that has to be removed) to get the other top loader bolts was corroded and bulging out ward, could this contributed to this "water" contamination ? We disassembled everything and inspected & cleaned it noticed a couple of small bits of metal chips approximately the size of watermelon seeds but couldn't see any damage internally to any gears or bearings. Cleaned the magnets and reassembled the axle filled all oil valleys and cavities with gear oil, phoned the local Mack dealer or the recently De-Macked dealer ( They sold Mack trucks since they opened 40+ years ago) Maybe Volvo thought they weren't selling enough trucks? Maybe the Mack trucks were tougher and lasted longer? I don't know, anyway back to My story asked service manager about My "water" problem He didn't have a clue, then I asked about gear lube and was told that 80/90 regular would be fine or synthetic would do just DON'T mix them together. I had read some post on here where an axle oil additive was recommended from Mack, asked Him about it He said that " He's never heard of it" before? I would like a part number if someone has it available? We took the truck for a test drive (30 miles) everything seems okay no "howling" or was it a long day at work I heard? I didn't get an oil sample sent out to analyze the content of it. The cover on the second drive axle was also bulging out removed it cleaned it reinstalled it rear axle fluid was fine no "water" Has this ever happened to anyone? or am I driving a submarine?