From the article: “The team also noted that the carbon dioxide could accumulate in the system, for instance, through the combustion of lubricants.”
A properly designed piston and piston rings can result in zero burning of oil. I’ve owned two such vehicles. A 1970 Ford Torino that burned zero oil, as the level on the dipstick stayed the same for 2,000 miles. And our currently owned 1997 Silverado with 197,000 miles that also burns zero oil.
I also have a CaseIH diesel tractor with 4,000 hours that burns zero oil.
My only concern with hydrogen is the safe storage and more importantly the distribution and metering systems to the engine intake. I believe leaks would be more apt to occur in those systems than the storage tank.
I have a 4 cylinder John Deere diesel in an air compressor that literally and truly loses no oil over 300 hours. I mean not so much as an eyelash on the dipstick. The machines air end is the same. It takes 2 and a half gallons of 6000 hour oil and even though it is specified to push some fraction of oil out the nozzle I never have to top it up. I kept up with filter and oil changes since I bought it new. It is the only machine I have encountered in the industry that doesn’t push a quart a month out the airend and past the piston rings.