is regular 10W40 okay to use? what's good/best oil?

[Kerry]

dont think he meant literally water [...] i think he meant the oil get's too thin??

OK, gotcha.  I took it too literally.

I don't get the impression that this person is "selling" anything, so I'm sure he's being honest about his perceptions.  But there's something missing.

* Does he work on used bikes that have been sitting in the garage for several seasons?  (They may indeed have water condensed into the crankcase.)

* Does he work on bikes that need an oil change every 2 or 3 months because the owner puts on a lot of miles?

* Does he have any way of knowing which bikes coming from which situations?

* Does he know what kind of oil is in the crankcase when the bike comes in?  (Car vs Bike, 5W30 vs 15W50, etc.)[/list:u]Most mechanics never get the chance to even

ask such questions - they're just handed a bike and told to fix it.

I guess I'm just uncomfortable with such a vague, blanket statement.  I prefer observable facts, gathered specifically from a GS500.  

[Kerry]

How 'bout Mobil1 10w-30?  I use it in my car and it's relatively cheap(for a synth) at Costco.  It's what I have laying around.

I don't see why not.  I believe the owner's manual lists 10W30 as well as 10W40.  They recommend one over the other at ceretain temperature ranges, but those ranges significantly overlap.

Also, how many quarts does the gs take?

A little under 3 quarts:

[Dom]

Thanks Kerry  

[TheGoodGuy]

this weekends riding with Castrol Super RX diesel oil or whatever its called.. I got excellent results.. i suggest that over Castrol GTX. I found the shifting more precise.

[The Buddha]

i asked some people about using car oil for the bike... he said car oil's not design to work with the transmission and clutch and everything... so in a while... it will turn into water...

That is extra funny ... cos oil gets thicker and thicker ... oh yea with the thing getting hot it behaves less and less viscous with age... whihc makes it get hotter ... making for a vicious cycle or is that viscous cycle ...  but when cold its more and more viscous due to impurity and the lighter additives burning off ... so with 3K when cold you have oil that dont want to flow and at temp it doesn't lubricate as well... double whammy...
Cool.
Srinath.