I keep a notebook to log maintenance done. Oil changes especially. I also stick to an oil & filter change every 25 running hours. The 10 & 14 hp Kohlers only take shat, 1-1/2 quarts, the Onan & Kawasaki both have filters and take 2 or 2-1/2 quarts. On the Tank zero turn I've kept yearly rub cards, and log days I mow, and how much and which tractor, years past I'd use my #72 sometimes and the 982 sometimes. Everything except the #70 has hour meters and and the hours when serviced get logged in my oil change notebook.
Dad had a little notebook he kept in the one enclosed storage area under the gasoline storage barrel with the oil, fuel and oil filters and grease tubes. The old FARMALL M's and H's didn't have hour meters but we ball-parked the run times and serviced accordingly and it worked. When we got newer tractors like the Farmall 450 gas, we'd log the hours for oil/filter change and just grease things occasionally. The 4010 diesel was an exception, when we first got the 4010 and plowed with it first spring it was burning 4-5 quarts of oil per tank of fuel, Dad would keep mental track of my field time and run out 2 quarts of oil and a can of soda for me and we'd do a "running pit stop", add the 2 quarts of oil while idling the engine. When we did lighter work like cultivating I burned less fuel AND oil, a major engine overhaul stopped the tractors excessive oil addiction.
May of 1968 Dad traded my '39 H for a '54 Super H the Big Time Operator had had since 1955, it was traded for a brand new 756 diesel, I bought the parts needed to install a tach & hour meter on it and it was serviced by the hour meter, we put around 250 hours a year on it. Now days as my #1 snow mover it gets around 4-5 hours a year and oil & filter & greased every 3-4-5 years.