Have you checked to see if you have an oil filter in your system? I have S25 Poulans from the mid 70s and 80s and when one stopped oiling I found a sponge looking filter in the pump area clogged with sawdust it had filtered from the contaminated bar oil (from not cleaning well before adding oil).

Naphtha has always been my cleaning solvent by choice. Due to the cost these days I will use cheap paint thinner. On cleaning ext parts that will be wiped or washed good (due to a varnish etc I notice the thinner separates into in my plastic cleaning container). Gas might be cheaper and possibly do a good job but more dangerous. Diesel fuel might be an option?? loger

The exploded drawing I have shows some kind of filter inside the oil tank and suggests periodic inspection.. But the drawing does not show how to get at it for inspection or replacement. Because I don't know what I'm doing, I've been reluctant to just start ripping and tearing. Some folks on chainsawrepair.createaforum.com suggest flushing with K1 and then running saw with blade off using K1 as bar oil 'til it flows well. Probably going to try that. I'll let you know how it goes. Thanks for your help!

If an oil filter is in the oil tank as fuel filters, you might be able to see it or and fish it out with wire or needle nose pliers as I do the gas filters. Hopefully a Tech or someone with personal experience will jump in and share some info on the filter.

K1 is new to me, flowing is the goal. I'm so out of date!! loger

Oliva you have been reported as a schill , stick to op,s question . Answer , Kerosene is the proper solvent to use for flushing oil reserviors