Despite the fact that this thread is 2 years old, I am not sure if this is a rethorical question.

Are you telling me that Amsoil is better than Wal-Mart oil for our 20-30 year old engines?

On what grounds do u make this statement and what's the statistical background if this is your claim? Why pay 5-10 times more for your oil?

Hello !
Next input to discussion.
Gulf Racing 10W-60 put in the engine after use of engine flush, K 1100 RS from 1995.
Oil change on 4.04.2011 @ 99261kms
actual 103840, mean while added 1,25 liter of oil, that gives 0,273 l /1000 kms. That bugs me a little.
Usually engine was burning oil down to level of center dot in oil check window. Previously on Motul 5100 15W-50 estimated consumption was around 0,2 l/ 1000 km. Back then a friend mechanic and old Brick user told me not to worry and use the privilege of "upper engine lubrication" . Now I start to think about switching to 15W-50 or 20W-50. The motorcycle is used mainly in the city, 2 x 10 kms a day.

Best regards,

Then the engine never gets to optimum temperature. Do you once in a while take it for a spin and warm it through properly?

Oh yes once a week, a ride to puff out spiders form exhaust.
Do You have any suggestions how to choice the oil for such conditions of riding? Recently I was thinking about switching to some cheep (yet brand) oil and change in each 6000 km instead of 10000.

Best regards

That's what I would do.

Ok, i will throw my few cents of Opinion into the ring...

I'm riding a K11LT (95) alsmost in the same conditions. Mostly dayly rides <=10 km twice a day.
I'm just checking regular on the grey oil rest at the Fillincap as one reason for urgent changing the oil.
Almost riding a longer way she will need oil refill when you drove long distance over 5k rpm's.
To all this i'm just changing the oil at about 5k-6k kms instead of 10k kms.

What happens is that moisture accumulates in the oil. Probably the bike is using a little bit, but you don't notice it as the moisture 'fills up' again. When you take it for a longer spin the moisture evaporates out of the oil and suddenly you see a lower level. Further I have noticed that when I try to keep up with my friends I end up braking a bit more 'on the engine' and the bike uses more oil then. YMMV.