Honestly, people. Has anyone ever had the experience of doing reasonable OCI's using any respectable oil on the market and had an "oil-related engine failure"?. I haven't. Nor has anyone I've ever known, and I'm 50. For example, about 20 years ago, a cousin of mine left some non-synth oil in his 1980 mustang long enough that it would have trouble idling. He then realized he hadn't changed the oil in about a year or so. He changed it out (it ran like water), and the car ran fine again. I think that car had about 150,000 to 200,000 km on it at the time. The car finally went to the wrecker's when the body rotted out.
So, worrying about a slight grade difference of oil (0w-20 vs 5w-20) is just a waste of time.
I have a 2000 Honda Oddysey van (168,000 km)that I've been running 0W-40 M1 in for the last 5 years (used to use M1 5w-30 -Honda spec). It actually sounds happier with the heavier grade (less mechanical clatter). It doesn't burn any oil between changes (8000 km) and the oil stays cleaner in that interval, as it has extended drain capability.
If the 0w-20 oil is hard to come by, or is too pricey, using the 5w-20 oil which is usually cheaper, has very similar characteristics, and is more obtainable, will do just fine. The important thing is to keep it changed out on a reasonable interval before it gets black, smelly and oxidixed.