I bought my first 066 in '92..one of the first ones our area got (Magnum, redeye, dual port, 25" bar). At that time I was cutting full time on a crew that took out Almond and Walnut orchards, getting paid by the cord...cut, split, piled at the stump, brush piled between the rows. Some of the guys would literally burn up 2 saws a year but most of us got many years out of our equipment. We cut around 6hrs a day, 6days/week depending on weather and usually ran 2 saws, trading off each tank to let them cool down. I did around 3cord/day for a couple years with the 66 and eventually stopped the full time gig. I've probably cut a couple thousand cord of wood with this saw by now from the small hardwoods (Almond) to big oak to 6' diameter and big pine in the Sierras every summer. I've worn out 4-5 25" bars a 36" and one 42" over the years...God knows how many chains Originally I ran Stihl mix but switched to special synthetic stuff and higher ratio recommend by Dozer Dan several years ago when I had him build my 346xp. The 066 is stock but other than opening up the muffler a little more.I'd like to hear from some individuals that use a 660... Either professional use or just home firewood cutting. A friend of mine said the bearings and crank only last about a year! He doesn't have one but that's what he heard. I've had one for several months with no issues. I think that's all BS but I'd like to hear from some professionals.
I still have it and use it when I can...don't cut nearly as much any more...maybe 50cord a year mainly for a resort in the mountains + what I burn. I replaced the piston last year but that's about it other than general maintenance.
If your buddy blew a crank/bearings in a year he either used the wrong mix or used a crappy air filter.