You can use several length bars on this saw. It looks like it came from the factory with a 20" bar.
20 in. Bar
The Stihl chainsaw model 08S has 3.75 horsepower or 2.8 kW. The displacement is 60.3 cc, the length of the bar is 24.8 inches, and the weight is 15.9 pounds.
An 18" or 20" bar would be ideal on a Stihl 041 http://store.chainsawr.com/
Some Stihl chain saws have an adjuster underneeth the saw to turn up the oiler .
Not satisfactorily. The 021 is a lightweight saw.
A STIHL 045 av is 75cc and the max recommended bar size for it is 32". However... If you have a 045 av Super then it would be 87cc and the max recommended bar length would be 36". So it depends if you have a SUPER or not. It is easy to tell as it will say SUPER on the top tag right below 045 av.
A chainsaw can be measured by Engine size or Bar length. Both are important to the weight and cutting applications
I have an 034AV Super and it came stock with a 20" bar. An 034 isn't quite as powerful (56.5cc vs 61.5cc), but a 20" bar should still work great on it.
Can I put a 18inch bar on a stihl
The 066 is the only size that Stihl does NOT make a carrying case. It is too high and too wide for the standard case. In addition, it has a 27"+ bar and most cases can only handle up to 24".
An 042AVE is 68cc and generally will run a 16", 18" or 20" bar. They use a 3/8" full profile chain that has 60, 66 or 72 drive links respectively depending on bar length.