when did stihl go from 40:1 to 50:1?

[slowcar281]

I was at work and was looking through some old folders and I saw where someone had filed away some instruction manuals to equipment, one of them was for a stihl ts350 cutoff saw (I think) so I flipped through it and was surprised that they recommended 40:1 instead of the 50:1 ratio. I looked all through the manual for a date but couldn't find one.

There was also a manual for a homelite chainsaw (not sure what model) and it was copyrighted in the early 80's so i'm guessing the stihl was dated probably around the same time.

So when/why did they switch over? I'm guessing emissions had something to do with it probably

 

[1Alpha1]

I can't say as to when the change over occurred, but I was suspicious right from the start. I'm sure EPA had something to do with it.

50:1, even with today's new fangled full-synth. oils, still makes me nervous.