First oil change - stick with what was used before?

[Roadinator]

This will apply mainly to the yanks...

I know it is a basic question, but want to make sure I am heading down the right road.  First oil change on my "new" '05 tiger with 50k.  Previous owner has a history of using Rotella Synthetic.  That's all I know from the notes, but it looks like at least three or four years of use, so I am guessing I should stick with using that.  Any reason to switch at this point?  I stopped by the auto parts store and saw Rotella T6 Synthetic oil that said for a diesel engine.  Looks like I can find one that says "Heavy Duty Engine oil" not sure if there is a difference between the two?  The Tiger is a wet clutch system?  I thought using an engine oil with additives was not good for wet clutches.  Anyway, I also noticed they only carry 5w40 gallon jugs.  Looks like it takes 4.22 qts, so I will be picking up some extra.  Do most folks fill up there oil filter with oil when installing the new one?  I picked up a K&N filter as that is the only thing the very small, use to be a triumph dealer close to my house had in stock. 

Thanks for your opinions!

[Stitch]

Diesel oils usually have higher zinc and phosphorus content (ZDDP). Many people have not had any issue what so ever and since you have a "history" with the Rotella synthetic without clutch slip, I think you will be fine IMO.

Most motorcycle oils carry the JASO MA-2 spec now which is suitable for wet clutch applications. Most newer oils are going to environmental friendly route to reduce the zinc and phosphorus content. I would encourage you to look at the back of the bottle of rotella you intend to buy and search the oil specs with the manufacturer online that are printed on the back of the bottle/jug. The difference is going to be the additives and specifically the right ones to use with a wet clutch.

As for the multi-grade weight, that depends on your environment (specifically temperature). 5w when it is cold (thin) and 40w at operating temperature.  Due to my environment, I run 20w50 year round without issue. You may be just fine with 5w40 if you live in a cool climate. I use K&N filters and enjoy the hex head when I have to change. I did install a set of rare earth magnets on the outside of the drain plug and filter to help attract any metal contaminants that may be floating around.

[Roadinator]

Thanks Stitch!

[Dutch]

I prefer a semi-synthetic 4 stroke motorcycle oil. Weight depending on manufacturers recommendation. In case of the cast wheel Girly 10W-40 or 15W-40. Imho 10W-40 is perfect for most conditions.