The EU has been at it today, and the G7 will follow, we're told. We can easily state what they think it means. Shippers of oil will not qualify for "western insurance and maritime services" if they are buying Russian oil at more than $60/bbl.
Well, some folks say the Russians can only get ~$50 for their oil on world markets anyway. But aside from that: since nobody running Russian oil at, say, $65 will feel obliged to, errr, tell this to the authorities - dear me no, guv'nor: $59.95 and not a cent more, look at my paperwork! - the most they'll suffer is presumably that the cargo will only be insured for that lesser amount. OK, so they'll screw Russia down another dollar for their pains, but no big deal. Or the Chinese will insure them. (Good luck making a contested claim on that policy, though.)
All this "capping wholesale prices" in liquid global markets is crazy. The EU is at it again with gas prices, though that's even less meaningful - they will only be "capped" by governments stumping up the difference between actual import prices and whatever cap they come up with. And the UK may end up getting subsidised EU electricity, as a delightful quirk of the rules, haha.
Incidentally, several EU nations are beginning to get fed up with Germany using the power grids of neighbouring countries to keep itself in imported electricity, and are limbering up to take steps to stop them. Most serious of all is public sentiment in Norway, which hitherto thought it would be great to sell even more of its cheap hydro power into Germany (and other countries, but mostly DE). Well, the hydro producers and the Norwegian grid (which coins transmission fees) still think that: and the taxman, too. But Norwegian consumers have noticed that the export of a load of electricity means the import of German power prices! And on this particular export, they aren't trussed up by EU rules. Watch this space.