I have that engine on a Craftsman I purchased back in 2000. I have an hour meter on mine, and it shows that I have just gotten to 500 hours on it. This is my second hour meter; they have a nonreplaceable battery that lasts a little over 5 years.
I have always used Mobil 1 oil, usually 5W30, changed once a year, at about 60 hours. I use my mower almost year 'round, cleaning up and bagging leaves thru the winter. The oil has always been right at the full mark on the dipstick, never using any oil in a 60 hour OCI. I tap dirt out of the air filter frequently, and change it once a year.
The trouble I have had with this mower does not concern the engine. I have had to replace all 4 wheels as the rears split apart about a year apart 4-5 years ago, and replacements were about $16 each. It is a front wheel drive mower, and the fronts wore off smooth about the same time, and I replaced them. These wheels have the plastic gears, but that part has given no trouble. The big repair was the gearbox. It cost about $70, and I did the work myself. The old gearbox had become filled with grass and other debris for some reason, and the gears were worn nearly smooth. The new gearbox came complete with a new axle, already attached, and did not look like the old one. The attachment points were the same, however, and it has worked just fine for the last 4+ years.
You know, in years past, I would have thrown this mower out instead of repairing, but I am now an old man, retired for almost 9 years, and have plenty of time to do this kind of work. And, I want to see just how long this Honda engine will last, and what its failure mode might be. It has never shown any sign of carburetor trouble or failed to start. I have replaced the spark plug only once, last year. I am afraid that the recoil mechanism for the starter rope might be starting to malfunction, as just the last time I used it, last week, it was reluctant to rewind. This was the first time it has done this. I have already priced a new starter, complete, at $47. This might be my next repair.
A Check of Sears ads shows a mower that looks just like mine, same features and Honda engine, for $289.95. This is the same price I paid for mine back in 2000.