If the chain isn't getting enough oil the chain and cutters will look like dry dirt is baked on, or like how a dremel grinding stone or sander gets burned on wood plugging the surface. Sufficiently oiled chains generally look clean. I like to set my oil pump so it runs out at the same time as the gas. I might even not top off the gas tank all the way, so oil doesn't run out first, and to avoid spilling gas all over the saw. I look at the top of the chain where the links connect to see if it is oiling well. After making a cut and letting it spool down after the cut, or with a very short rev, I should see the spots above the rivets look moist. Or, I'll pull the chain out of the bar enough to see how glossy/wet the drive links look if it is a stingy oiler.
Lately, I've been adjusting the oil output based on how dirty the saw gets, if I feel like it. Stihl saws seem to stay so clean looking for a reason: because they don't oil much. While Echos easily get caked in oily fine sawdust.
I remember tapping in the pin on a 661 that lets you turn the oiler screw to max, and it wasn't long before that saw was covered in oily dust and leaving puddles of oil.
I have recently wondered how much wear can be reduced by more oil. I used to think the main cause of bar wear was metal on metal contact with the chain. Just enough oil should help the bar last a very long time. But, how often do you pull the saw out of a cut with the chain stopped to find it packed full of saw dust? Those little wood chips get caught by the drive links and drug through the rails. They are what sucks the oil off the chain so fast, and in my opinion, they wipe off some metal in the process. Just think how hard it is to free up a chain seized by sawdust jammed in the rails. My fast cutting firewood saws have it bad because the chips are so thick, they can dry out a 20" bar on a heavily oiling 90cc such that I have to keep the chain spinning between cuts to keep it from seizing. Actually, the 90cc saws tend to have enough torque for it to not be much of a problem, but I was testing an Echo 590 I ported and had a fast chain on, and after every cut through a 30" Ash log with a 20" bar, the chain would seize and take much effort to get freed and lubed enough to start another cut, but it went through a tank of oil with a tank of gas. That's when I started to realize the effect of sawdust inside the bar groove since my only variable was the size of the chips.
