I just got a LLY/Alli and have abot 900 miles on it now. At what miles can I tow something? 500? I plan on pulling about 11k.


Is there anything I should do before or after I tow, i.e., change rearend fluid, etc?





Thanks.

The owner's manual says you should keep the speed under 50 MPH for the first 500 miles of towing...http://www.dieselplace.com/forum/smileys/Ermm.gif


The explanation is that they feel the rear end ring and pinion gears will wear in some more with the extra weight. That wearing in, or break in, will create quite a bit of heat in the differential which might cause problems with seals or in extreme cases, galling of the gears.


Some here have ignored the break in procedure and reported no problems. Some have followed the procedure and reported no problems.


I've always believed in a break in period and there's got to be a reason it's in the manual, so I followed the 55 MPH restriction for the first 500 miles on mine. I don't know that I'll keep it to 50 MPH for the first 500 towing miles since I think the majority of the process is completed in that first 500 miles, but I don't think I'd push it real hard for at least a few hundred or so pulling that kind of weight.


After you get the 500 towing would be a good time to change the rear end lubricant and that's a whole 'nother story about what to use. I bit the bullet and bought the GM grape juice so there's no question on warranty. GM list's their own spec for that lube in addition to the GL5 spec for synthetic differential lubricants.


Just my two cents...http://www.dieselplace.com/forum/smileys/Embarrased.gif

First things first......... check the diff fluid. Some trucks have shown up about 1qt or so low. If you will be towing a fair ammount...... get some Bilstiens shocks. The shocks make night and day difference towing.





Burner

Thanks guys.


So, should I not change the rear diff fluid until I complete 500 miles of towing?

500 miles "no tow" and 500 miles "slow tow" should work fine. Remember, jump starts can be hard on the parts as well.


Change the fluid @ 1,500 miles. Might even want to think about a diff cover. http://www.dieselplace.com/forum/smileys/Approve.gif





Burner------------------------> http://www.dieselplace.com/forum/smileys/Big Smile.gif

Change engine oil and rear end oil both at about 800 to 1000 miles and go tow. Do not get to agressive (going for max pulls) until you get a few more thousand miles on it. I would then change engine oil at normal interval and change rearend oil again (it should be fully broken in by now) and rock and roll. No need to chage rear end oil again for a while after that (use interval recommanded in your manual)

I hope you don't mind my two bits. The 50 and 500 mile theory was developed twenty some years ago and has never changed even though technology has. And origionally developed for gas engines, you will read the exact same statement in the manual when u purchase a new car with a gas engine. How can the same theory work for completely different engines. Would you want to be jumping on a freeway doing 50 being passed by everone else who is doing 70 +, dangereous.


You will not void any warranties as long as you do not exceed the manufacturers gvwr or gvcwr. The newer method is to drive around town for a few miles. Meaning, accelerate to about 30 mph for a mile or so and then stop (do this several times 3 to 4) Then accelerate to 50 for a mile or so and then stop (do this several times) Breakin' is complete. The 'manufaturer' breakin was origionally developed to seat the rings. The above procedure has been found to be more effective as well as more benficial to the engine.


Very rarely does anyone change the rear diff. fluids at all. follow the guide that the manufacturer provides for service intervals. oil changes can be extended by additives or shortend by use of the wrong viscosity of oil. I use Lucas additives in chevy suburban with a 454 gasser and change oil every 5-6000 miles and have over 200,000 on the truck with no major component failures.


I look to the trucking industry, as I am a long haul trucker, for what works and doesn't. I picked up a 2004 Freightliner Columbia w/ 10.4 miles on the odometer and hooked up a trailer with a 40,000 lb load and transported it 2000 miles down the road. Of course my engine doesn't break in till around 100,000 miles. Yes different vehicles but same engine concept and same technology.


Sorry to be so long winded lots of info to convey. Lots of good advice given on this forum.http://www.dieselplace.com/forum/smileys/Geek.gif

I have changed enough diff oil to see how "dirty" it gets in break in. (feels griity). Yes some peolpe do not change it but it can make the difference between one that is quiet and stay quiet and one that develops a little gear noise in its life and has a shorter life span in heavy use. It is cheap insurance to change this fliud at least once early on.Edited by: snoman

Thanks guys.





Sam, I agree with you that the 50/500 is the same in all the manuals, no matter what the engine or application...., so you kinda lose faith in it being that accurate....http://dieselplace.com/forum/smileys/Disapprove.gif


I am at around 1300 miles now and I plan on changing the rear end lube, engine oil and filter, and Alli filter before 1500 miles....

I would recommend changing diff lube after a few thousand miles. I was appalled at how much grit came out of mine at 14,000 miles. I should have changed sooner. I put in Mobil 1 75w/90 and drove another 18,000 before changing again in anticipation of heavy towing in hot weather. I switched to Redline 75w/140. When I drained the Mobil 1 from the diff it was black (to be expected) but grit free.
TC