Couple of questions and a big thank you to all who contribute so much good info.
Had I not been reading about and had an idea what to expect I would have been very surprised to see the gray and foamy oil that I just drained at 12,500 mi. Thanks for that.
#1 I picked up some SHELL SPIRAX-S 75W-90 (full synthetic) at my local petroleum store. GL-5 rated and says it meets 500,000 mile drain interval for Dana and ArvinMeritor heavy duty over the road axels. I've never noted this product mentiond here but it sounds good with military, API and MT-1 specifications. SOUND OK?
#2 Has anyone thought about or actually drilled and tapped a 1/4" pipe plug in the small sump area in under the ring gear?
I used to do this with my dana 44's but looking for advice on this one.
After years of working with the 44's in my jeep these gears look huge!!