Oil level. (four stroke engines only) Checking your oil level is not a simple matter when in comes to motorcycles i.e. should the oil be hot or cold, is the oil level checked in the crankcase or in a separate reservoir (a dry sump), should the dipstick be fully screwed in or not, must the bike be on the side stand or simply 'level' and does the bike have a dipstick or a sight glass? All this adds up to reading the manufacturers handbook very carefully. An under filled crankcase can be disastrous while an overfilled one may flood you air cleaner with oil.

You should also know the difference between the 'low' level and the 'high' level and how much is TOO much

Here are some pointers regarding oil which are true for most motorcycles

The bike should be level as possible, except for some that are checked on the side stand.
The oil should not inspected cold and is therefore best done after warm up.
Do not allow foreign matter and dirt to fall into the sump during the inspection process
With threaded dipsticks do not screw the dipstick in when taking a reading
High temperatures, time, speed, heavy traffic, short trips and dust quickly destroy the quality of your oil
Change your oil every 3- 5 thousand miles or 6 months, whichever comes first except in dusty conditions.
Never use a pirate oil filter. An excellent quality pirate unit can still destroy your engine as its "Bypass Filter Rating" may be incorrect for your particular model causing the oil to circulate without the benefit of being filtered. Thus, use only the one from your manufacturer for best results and long life.
Motorcycles can use the same oil as cars although the motorcycle specific oils contain additives for better oil performance in them .Special synthetic motorcycle oils are available for sportbikes that are ridden hard. Note that synthetic oils are not recommended if your bike has a wet clutch (a clutch that runs inside the oil in your crankcase) In most instances a semi-synthetic oil graded as SAE 20 W-50 is usually fine, a lot of people have gone back to the HD primary oil for this, it's been tried and proven for many years.


Source: http://riderinfo.com/forums/showthread.php?t=379