After the service, I took a look at the fluids in the car. There is a tank marked coolant with F and L marks on it, and the the level of fluid in this tank was (significantly) below the L mark - it looks like there are about two cups total at the very bottom.
This means that you can book a round-trip ticket to Hawaii from anywhere Delta flies in the US, Canada, Mexico, Puerto Rico, or US Virgin Islands using Korean Air miles for only 25,000 miles in coach or 45,000 miles in Business Class.
But hereâs the part that needs more clarification: This is not one 500-mile upgrade per flight, instead itâs per 500 miles flown. That â500-mileâ part of the description refers to how many miles the upgrade can be applied to. In other words, you need one 500-mile upgrade on a flight equal to or less than 500 miles. But anything above 500 miles would require another upgrade. For example the flight from Dallas to New York is about 1,400 miles and would therefore require three of these 500-mile upgrades.