i recently did some welding on my 05 (2wd 3.73 ls) rearend. i see by the other threads that 75w-140 syn is recomended? But my real question is do you guys think i really need to change the oil? i only have about 6000 miles but i am concerned that i may have burned the oil a little when i welded the brackets for my air bags and 4 link susp. to the axle tubes. during welding, the axle was level, and i only welded about 2 inches at a time. approx 8-10 inches of weld on the middle section of each axle tube. one bracket goes from top to bottom of tube, the other bracket goes middle to bottom of tube. on both sides. what do you think. (as i was writing this post, i realized the answer is probably, most definatly, yes. but thats just me.)
thanks for input.
john

 

I believe I would change it. If the truck has 6K on it, it probably has never been changed. Good to get that initial fluid out of there anyway in case it has any "new parts" filings.