"There is also the aspect of doing a short UOA at only 1000 miles being skewed by the left over oil from the last oil run. Depends on how much old oil is left inside the engine to mix with the new. What he should do is get a UOA on the new oil fill within a short interval, like 25 miles or less so that will become the more accurate baseline for the new oil run."
This is a great idea. The previous oil was in the truck for around 6,000 miles before I dumped it and put the RL racing oil in there. I wonder how much of that Fe was left over from the much longer, previous run. I have decided to perform this suggestion. When I drop the 0W-20 in there now I will get a UOA. I will be going to a 0W-16 next. I plan on getting another UOA after a hundred miles or so. It should give us an idea of the "left overs".
I need to make things a little more fair during the collection. As I need to withdraw the oil out of the dip stick tube at 100mi into the new oil I will do the same just before the oil change. Normally I would get a mid stream sample when dropping the oil.
Anyone have a better idea for a collection method?
Ali