Here are a few of the initial announcements on fuel surcharges to compensate carriers for the IMO2020 rule requiring 0.5% sulfur fuel or equivalent scrubbing equipment. The current gap is $171.00 between MGO and VLSFO as seen on this graph from shipandbunker.com where you can add several grades to the graph. It’s a 20-port average reported here. A useful site.
You can see from the article that the firms are soft-pedaling the surcharges to keep from losing too many shippers. Probably a good strategy at the start. I believe long term as refineries gear up for LSFO that the spread will narrow.
And of course you don’t have to buy MGO, you can use the dirty fuel which is cheaper.