Oil threads get about as many differing opinions as tire threads. I read in the Ram sections all day long where guys swear synthetics are no different than the cheapest conventional oils. One guy will post a report that shows say Royal Purple doesn't protect as good as Wal Mart branded conventionals while another will post a different report showing the same RP protects WAY better than even most synthetics.

No way of knowing without testing.

Jetster:

Your viscosity was on the thicker side of normal, but fine. When I had Amsoil tested in my '98 Ram (5.9 V8) at 12,000 miles it was more inline than what the testers in the report I linked found. Not as extreme as their findings, but out of range by a good bit. The reason I tested it was I always ran my synthetics for 6000 miles and wanted to see if spending the extra $ on Amsoil and going twice my normal interval would justify the added cost of the product.
Now I will add that at that time I was younger and off-roaded a good bit. Fished and hunted easily 4x more than I do nowadays and towed bass boats to tourneys all over the southeast. I "retired" from tourney fishing about a year after purchasing my current Ram (which I've never tried Amsoil in). So I know I was harder on my 2nd Gen Ram and it's oil than I've ever come close to in my current truck and probably did a lot more dirty, dusty off-road driving and hauling than you do with your Dak. Not to mention comparing a Ram with an engine designed in the 1960s to your truck is like comparing apples to orangutans. Again, a good reason for individuals to test their oil rather than relying on someone else's testimony.

Again, this is why you have your oil tested...