SN is the current spec (effective october 2011). I'd go with the s* spec oil called for in the manual (but NOT old oil that's been sitting on the shelf for that many years), motorcycle oil, or the rotella T6. the newer specs use less and less zinc, phosphorus, and other stuff that help reduce damage in no/low oil situations (startup) but damage O2 sensors and catalysts when cars start burning oil.
using the wrong viscosity (30 wt) oil won't cause the clutch to slip, it'll cause the oil pressure to be way too high at first, then a hair low when warm. (the 30 means the base stock is thinner than a 40 but the 10 means it's a LOT thinner when cold: honey vs. molassis)
oil with the wrong additives will cause the clutch to slip.
out of curiosity and maybe to help convince you...why did you use straight 30 weight oil?