Yes, you can use 20W50 in most OPE in the summer time and the unit will survive fine. However, if you are already loading the machine heavily, 20W50 will make it worse. Not the end of the world, but certainly not an improvement.
We had a neighbor lend us a log splitter a decade ago. I'm pretty sure the unit had a big Tecumseh flat-head on it. Thinking I was doing him a favor, I changed the oil in the engine about mid-point through the big job we were doing. I used 20W50. You could hear the engine labor more when we began using it again. Before we gave the machine back to him, I changed it back again to some form of XW30.
For most OPE, an XW30 will work best and there are plenty of them out there, some even in HDEO flavor. If you are running something that burns oil or are torturing your engines, consider stepping up to an 5W40 or 15W40.
20W50 is simply not a very good choice.
