Just a few quick questions for the multitudes (that have a better idea than I do), after a fairly long highway run is it normal to have an odor like gear oil near the left rear tire. I am under the impression that there is a vent line from the rear end and it may lead to the left (haven't had time to crawl under yet) wheel well area. The truck has almost 40K (don't get to drive it as often as I'd like) and no I haven't changed the rear end fluid yet, I really haven't towed or hauled much of anything. They dealer replaced a pinion seal at about 24K after I hauled a car From the lower DelMar to SE CT and found gear oil all over the front of the trailered vehicle and rear end,so I'm a little concerned there's more going on than there should be. So in addition the question of should I be smelling that odor, how often should I really be changing out those fluids and is it normal for the rear end to heat up enough to vent off fumes running mostly empty on the highway for 6-8 hrs with stops for fast food and fuel?

 

Well no its not normal, have never smelled that on my 06, and I do tow, even on long days, no smell, I dont think there is a breather on the rear diff, you may have an axle seal gone, if I were you I would climb under and see if there is a leak around your wheels.

 

Any time that I have smelled the odor of gear oil it is because I am smelling it on the brakes from a bad wheel seal. It takes a little while before it starts to show.

 

Exactly, or I happen to notice it running down the inside of the rear tires.
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Yup, not normal. Time to pull it down and see what's up. There's a thread in the wiki that might help if you have never opened up the rear end before. (DIY rear brakes)

 

These gents have you covered well. Follow their recommendations.

 

Thanks for the responses, you've confirmed what I thought, I was just kinda hoping my gut feeling was wrong but as they say if doesn't look or feel right it probably isn't. Like I said the truck sits more often then I'd like, been told and have seen where this just isn't good for mechanical stuff, already had to replace the water pump because of a failed seal now most likely this one (probably do both to be safe), thanks again for the sage words of advice.