Update on a previous posting regarding Shell Rotella T6, and shifting problems on my Voyager...
I switched from the Rotella T6 Synthetic, 5W-40, to Rotella T, 15W-40 conventional. We had run the T6 Synthetic for a couple of years, but we began experiencing shifting issues where the transmission would 'miss' a gear, and we'd hit 'neutral', between 2-3/3-4/4-5!!! Did some research, here and elsewhere, and others had experienced similar situations -- rare, but there were other postings, on other web sites. Also discovered a comment about the minimum weight of oil being critical: oil adheres to the metal surfaces, I forget the technical term for this (film strength?), but it is critical. If the oil is too thin of a viscosity, it will not adhere to the metal, and you get metal-on-metal wear. I
suspect this is what was happening in my Voyager's transmission: the 5W, T6, was too thin, cold, and it was causing issues... Only way to test the theory, was to change the T6, 5W-40, for T, 15W-40, and see what happened...
I changed the oil a week ago, and we finally got the bike on the road Sunday. We put 300+ miles on the bike, and we had one mis-shift incident, but the wife says it was likely her error, not lifting fully on the shifter. We traded positions on the bike several times during our 300+ mile ride, and it shifted almost perfectly -- the issues seem to have disappeared.
I have nothing against synthetic oils -- I think they are a superior oil,
IF they are of the proper viscosity for the engine in question. The manual specifies 10W-40 for a reason: the 10 weight is the thinnest oil to be used to maintain an oil film on the metal parts, IMO, so I likely caused some excessive wear by using 5 weight oil (cold). Food for thought -- no scientific evidence, only some anecdotal, personal experience, for what it is worth. Cheers!