Now that you have your tiller and you've dug around a bit, you need to learn how to properly care for your machine. Tilling is dirty business, and as a result your tiller will require a little more maintenance than many other home tools. The first and most important rule for tiller ownership is to keep the machine clean. After you till, hose off the tiller, giving special attention to the tines. If you have any vines or roots wound around the axle, be sure to cut them off.
The tines themselves will become dull after a while, especially if used in rocky soil. If you have a lighter mini-tiller or a small front-tined tiller, flip it over and sharpen the blades with a metal file. If you have a large tiller, don't attempt to turn it over. In this case, remove the blades and clamp them in a vice before using the metal file. If you don't feel comfortable doing this yourself, you can always take the unit in for servicing about once a year, depending on how much you use it.
Because of the large amount of dirt and dust the tiller sees, there are two things you'll want to do with regularity: Change the oil and the air filter. Changing each one is something most handy homeowners can do themselves. There will be a drain plug near the bottom of the oil reservoir. Remove this plug and drain the oil into an oil pan while the engine is warm. Replace the drain plug and refill with new oil of the recommended grade. Then start and run the engine at idle for 30 seconds. Stop the engine, wait another 30 seconds and re-check the oil level. At this point, make sure that it reaches the full mark on the dipstick, and be sure to properly dispose of the oil at an authorized recycling center near you.
The same goes for the air filter. Look up the kind you need in your manual, and you can switch it out in a matter of minutes. Most air filters are encased in an easy-to-remove square plastic box. Change the air filter after every 18 to 20 hours of use or once per year, whichever comes first. The oil should only be changed yearly unless you use it more than 50 hours per year. Refer to your owner's manual if you aren't sure about which parts are where. And again, if you don't feel comfortable performing these routine maintenance checks, you can pay someone to do it for you.
At the end of the gardening season, run the gas tank dry before you store it. If you can't run it dry, don't attempt to empty the gas tank. Just head down to your local hardware store and purchase a fuel stabilizer, then use as directed. This will keep the gas from going bad in the off-season. Always store your tiller in a dry, shady area, preferably in a basement or shed. Sunlight can have negative effects on the tires, and moisture leads to rust.