I’ve seen plastic used automotive radiators and clutch hydraulic systems for over 20 years.
Wondering if plastic is the failure point of these chainsaws
Stihl saws are at least "Built in the USA" per the website however that does not address from where the parts are manufactured.
With that being said Stihl does us a lot of plastics but not all plastics are created equal. The plastics I see in Stihl product are good quality materials which are glass reinforced where needed. Just watch some AvE too teardowns so learn a little about the plastics and the use cases for specific versions.
Personally I have not been let down on any Stihl product I have acquired.....and that does back for a set of hedge chippers made in West Germany that I still regularly use
Ok, personal experience here. In 2006, I bought a Stihl Kombi tool and backpack blower (and a third tool that I've since sold). They each had nifty new quick turn gas caps that were supposed to be easier to install and less likely to come off in vibration than screw on caps.
Well, within the first year of use, the caps started to get tight, and were hard to install. Eventually, I had a situation on the blower, where I turned the cap, but it was so tight that the locking lugs failed to engage, so it was loose, when it appeared installed. When it popped off the tank, I ended up having my back doused with gasoline. That's very un-cool when you've got an engine strapped to you.
Shortly after that, I got a recall notice for the gas caps. It turns out that ethanol in the gas caused a part to swell, making them tight. I had to use pliers to get two of the caps off at the dealer when I had them replaced. The caps have been working great ever since.
I do still feel that Stihl engineering is quite good, and they're pretty smart about their use of plastics, but even they have run into unexpected issues over time.