I have a HRX217HYA and it calls for 08207-10W30. I can only find 08212-10W30 at the Home Depot I bought it at. Are these equivalent?
The manual says to use 4 stroke automotive detergent oil. What type of oil do other people use?
The numbers
08207-10W30 and
08212-10W30 are Honda part numbers, both for the same 10W-30 oil sold by Honda, and both of these are 100% suitable for use in your Honda mower. You do NOT have to use Honda oil, any brand of SAE (Society of Automotive Engineers) 10W-30 is just fine. As long as the bottle says "SAE 10W-30" you are good to go.
Also, it does not matter if you use petroleum or synthetic oil; either are fine, provided you change the oil per the Maintenance Schedule in the owner's manual.