Earlier Oliver typewriters had a smaller ribbon vibrator, hence the need for 7/16" ribbons for those machines. The later models, from the Oliver 9 up, had a slightly larger vibrator capable of accomodating the now-familiar 1/2" ribbons, so in that sense, it is correct to say that SOME Oliver typewriters used a half-inch standard ribbon.
I solved the problem myself using a very un-orthodox procedure: trimmed a new 1/2" ribbon to the right size for my Oliver 5.
Another, even more radical solution (but also more practical in the long run) would be to replace the original vibrator with a newer version, or try opening the clips a bit so that it can accomodate the 1/2" ribbon. Of course, this should be left as the last resort.
In this entry I describe how I discovered the difference in ribbon widths used by the older Oliver typewriters. Don't worry, it's still a bilingual entry: http://modernidadyobsolescencia.blogspot.mx/2013/11/poniendo-trabajar-la-abuelita.html
So, if you have some free time, you could trim a new ribbon using scissors and then use it on your Oliver. OR, you could buy 7/16" cotton ribbon like the ones used to ornate clothes and then ink it manually with rubberstamp ink. That would make a very decent substitute for the original ribbon.
