add different kind of oil
 

I haven't ridden the bike for a couple of weeks, and though I remember the oil level being close to the bottom, now I can't see it at all. I would just add some, but I don't know what kind of oil is in there. Is it ok to just add some oil, or should I drain it all and start fresh? Should I also change the oil filter?

Also, if I'm supposed to drain everything, the shop manual says to let the engine run for a while to warm the oil so it's easier to drain, but I'm not sure I should start the engine since I don't know how little oil is in there. So should I just add some oil, warm it up and then drain it?

Finally, if I need to change the oil filter, I supposedly need to fasten the bolts to specific torque values. How do you guys do that, I assume with a torque wrench? Do I need a different torque wrench for different bolt sizes? Does anyone recommend any tools in particular?

Thanks guys.

RE: add different kind of oil
 

Adding a little bit of off-type oil isn't going to hurt the engine. Just make sure you change your oil change at the regular interval per manufacturer's specifications.

In regards to the other questions, if you are in fact changing your oil it's helpful to let the engine run for just a couple of minutes since warm oil is more viscous than cold, meaning it wll drain quicker. But don't let it run too long or you'll get burned.

As far as torquing, any torque wrench will do. However for the filter, hand tight is plenty tight. No torque wrench is needed. As for the engine bolts, even if you don't have a torque wrench make sure the bolt has some oil on it when you screw it in, and tighten it so it's snug.... but that's it. Do not over tighten. You really don't need a torque to seat the drain plugs. Snug is good enough. With all that oil down there they won't seize up.

RE: add different kind of oil
 

when in doubt, change the oil (all of it)

and any time you change the oil, change the filter

my suggestion would be to add enough of new oil to bring the oil level up high enough to crank the bike for a few minutes, then drain and replace

torque wrenches use sockets so you just need the right size socket for the bolt

i don't have a specific suggestion for a torque wrench but its good to get one with a very wide range

RE: add different kind of oil
 

A clicker-type torque wrench is a beautiful thing. Snug is such a relative term and aluminum strips so darn easily. I prefer to have two torque wrenches -- one for up to 50 fl/lbs and the other for everything over that. If you look around they can be had for $30 or so.