Can a gearbox "get used" to low oil?

This might sound a bit daft but here goes. Started having a proper look over the bike (SV650S K2) the other day to see what I can do in the way of maintenance and tweaks myself (owners manual has been ordered through my local, friendly Suzuki dealer - CMW of Chichester, can't recommend them enough, Wifey's Ducati came from them and they've been extremely helpful) and I noticed that I couldn't actually see any oil in the sight glass. It's running fine, gearbox nice and smooth and no warning lights but I thought I'd better top it up. I had some proper 10W40 motorbike oil (as recommended elsewhere on this site) left over so I just put in enough to get the oil halfway up the glass.

The 'box has gone from being as sweet as a nut to being very lumpy. When I pulled up at work this morning, it disliked the very concept of neutral - I had to gently stall it, rock it in gear a couple of times and then it found neutral ok. As I said, is it possible that the box was used to running low on oil and is now behaving as though it were over-full? Or am I being a bit thick?

[Bibio]

you did check the oil level with the bike level and not on the side stand?

[andrewsmith]

you've overfilled the engine with oil.

As Bib said did you do it on the side stand or on a workshop stand?

I pulled it to vertical off it's sidestand while looking at the glass (yes, with no-one else there to take the weight of the bike, stupid, dangerous, don't try this at home etc etc) but I'm going to get somebody else to check it when I go for lunch, just in case it wasn't quite as vertical as I thought it was!

[mikerj]

All wet clutches drag a little when the oil is cold, was it still impossible to find neutral with the engine fully warmed? You might want to check clutch adjustment as well.

**Update time** Just been out and got someone to sit on it while I checked. The level is above halfway but still below the Full mark. The oil was, ahem, a little dark shall we say. Well, pitch black actually! I think this may be "Oil Change Weekend". Do you think Halfords will have the right filter or am I better going straight to a dealer?

[yorkie_chris]

Oil is normally black.

No the box can't get used to low oil. It doesn't care, only difference comes from clutch drag which can be caused by overfilled oil.

Make sure you are getting it perfectly vertical when checking. It is normal to do it yourself, just don't drop it on your head.

Originally Posted by yorkie_chris

Oil is normally black.

Yorkie, what I poured out of the bottle to top it up with was a lovely golden colour. I thought once it looked like crude, it was time for some fresh.

[yorkie_chris]

Oil has to catch all combustion byproducts, when it catches these it turns black. This will happen within 10 miles.

When you have done 3000 miles or so it is time to change oil. Worth doing as precaution if it's unknown when it last had some.

My numptiness knows no bounds! Of course it goes black. The gearbox oil I'm used to looking at was in my old NSR125 which is, of course 2-stroke, so the oil never sees "combustion byproducts" (unless something is horribly wrong). I should have been comparing it with car engine oil. Apologies for using the c word there, by the way. I think I will give it some fresh juice anyway - as you say, it's probably a worthwhile precaution. It's just not quite as urgent as I feared.

Home and back at lunchtime and the gearbox seems to have loosened up again, so I guess it was just the correct amount of oil taking a bit longer to warm up than I was used to. Thanks for the advice guys.