OK I read the manual and it doesn't say whether one should check the tranny fluid when the engine is hot or cold for a 2012 SG 103.
So should the tranny fluid be checked when hot or cold, or doesn't it matter?

 

Doesn't really matter.

 

Check when hot. When fluids heat up, they expand, AKA thermal expansion. Overfill and it will come out of the breather, or somewheres else. Underfill and lack of proper lubrication.

 

After owning several bikes over the past 21 years, I never bother to "check" the transmission oil between changes.

The only time you might need to do this is if you have evidence of a leak, and about the only place you really have to worry about a leak is on the primary side where the front belt pulley is. The pulley can work itself loose and the seal will give out, but if that happens, you've got more problems than low transmission oil.

I've been using Mobil1 75w/90 synthetic for years, and find that it pretty much comes out looking the same as when it went into the transmission.

The new 6-speed trannies are easy to fill, too -- just take a 1qt. bottle and pour the whole thing in, then put the filler plug back in...

 

Do you have a leak? If not its still in there.

 

Formula + is a oil I don't think oils really expand like atf when hot.
So like christo said I don't think it really matters if the bike is hot or cold.
The only thing that matters is letting the bike sit for a bit if you are checking it hot to let all the tranny fluid settle (run) down from the top of the inside of the tranny case.

 

Doesn't matter, just make sure there is some in there...

 

If you don't check your fluids something may not work the next time you need it.

 

Remember checking the trans fluid you wipe off the dipstick and put back in hole and do not thread it in like the engine oil dip stick. (At least on a 6 speed trans)

 

I agree with the others that say you don't need to worry about it unless there is evidence of a leak. There's no where else for it to go and it doesn't have the possibility of getting burned off like engine oil.

That's one of the best things they did when they made the capacity exactly 1 qt. Drain it, pour in a full quart and then put the dipstick back in. Done until next time.