I take delivery of my new Duramax todayhttp://www.dieselplace.com/forum/images/smilies/smile.gif. I just got my new Travel Trailer yesterday. How long do you recommend before I take a shake down cruise with the trailer. We were planning to in 3 weeks. I should have 300-500 miles on it by then.http://www.dieselplace.com/forum/images/smilies/hihi.gif

Thanks
Bob

Bob,

You should be OK after 500 miles, but I would recomend you change the rear diff oil before you go or just after your first run.

I did mine after my first trip, about 600 miles on the truck. If you change it after your trip, make sure the level is within specs before you go (IIRC 1/4" below the fill plug).

Do a search and you should find a lot of infromation on this subject, then decide.

Have fun.

This is how I did mine.
First 500 no load
Second 500 loaded, many short (30-50 mile)trips followed by cool down.
After the second 500, change the rear end fluid.

You will not believe what the oil from the first change looks like. I can believe that if it is left in, premature axle failure is almost a certainty