I did drain the front diff fluid, it was 75-90 synthetic that I replaced 8 months ago after buying this PF. I really dont' understand what could be vibrating/humming in there at highway speed but maybe someone with experience could chime in.Thanks...here are some pics.
Just pulled plug, has some muddy gunk on magnet.
Wiped drain plug clean with paper towel, black gunk wiped off it.
Drained front diff fluid after 8 months, still looked transparent while draining but has a muddy gray color.
Comparing used fluid with gunk from plug.
Poured used fluid in clear jar.
Lastly, showing new fluid vs drained fluid.
How does this used fluid look?
Any ideas about a vibrating front differential and humming/howling noise at 60mph or highway speed?
Once again a high frequency vibration felt underneath vehicle, distant feeling in steering wheel and had wheels balanced/alignment already. As I mentioned it was check and diagnosed at front differential but what is in the front diff that might wear?