Why not a full synthetic? Use the Stihl Ultra (full synthetic) at 50:1 and don't look back.
This ain't a 4 stroke...
Gary
You did real good I just sold a low hour 029super last fall for 200.00,,,and the guy loves it!!!
garys right on this one,,, It looks to have had a steady diet of Dino based oil and possibly regular grade Gas hence all the carbon build up,,
If it was mine,,, I'd get a small wire brush, a small plastic scraper From you pistol cleaning kit and some solvent (White mineral spirits works fine and is cheap) and carefully decarbonize that exhaust port with the piston up near Top Dead Center,,, especially near the piston interface w/port window,,, that carbon can cause problems,,, then flush it clean with a spray bottle and the brush from your pistol cleaning kit,,, LOLOL but my CAD is worse than yours,,,
Then/or,,,, LOLOL!!! put it on a steady diet of premium grade Gas (non ethanol if possible) with stihl Ultra and it will clean that baby up,,, Even if you dont decarbonize,,, the Ultra will clean it up!!! Any good synthetic designed for air cooled engines will work,, Amsoil, Etc. Etc.
Do a search on synthetic oil here and you will be reading for days!!!
That saw has seen very little runtime as evidenced by the still visible maching grooves on the piston/rings and the bar code tag that is still glued to the front of the crankcase/oiltank
From the looks/condition of the rings/piston Im thinking your compression tester may be off a bit, not unusual
Sharpen that chain and keep it sharp is you best friend,, Also get yourself a bar groove cleaner and keep the build up cleaned up in the guide bar groove and the oil holes clear,,, blowing the groove with compressed air will not clean the pitch that gets stuck in there,,, inspect the bar and make sure the rails are trued/square, dress as needed/required,,, Make sure the sprocket gets changed as needed and grease the pto needle cage brg. while you have it apart,, all you need for this is your scrench,/screwdriver a good pair of needle nose pliers