[Guy]

We use Delo 100 40 weight, as instructed  by Newell Gurus ! We order our oil at Orileys, and usually our order is ready in 2 days. I buy 3 cases at a time, each case being three 1 gallon containers. This gives me enough oil to prime the fresh oil filters, refill the " gentlemans" replacement oil resevoir , fill the crankcase to a bit below the full mark ( sweet spot on this coach) , and usually have an extra gallon to drag around for another 6 months.  We seem to use 1.5 gallons going coast to coast, so I guess we are a tad over a quart every thousand miles. 

I would gladly turn over the oil changes to Speedco or some other oil change company, if I could really trust them to put my Delo 100 40 wt in the engine. I have had the oil changed at local truck shops when I can watch.  The 25,000 dollar penalty for low viscosity oil being run in these old engines is a risk that really scares me.