Small Engines (Lawn Mowers, etc.): Craftsman self propelled, spray lubricant, adjustment screws

Question
Just bought a used Craftsman selt propelled 6.75 HP lawn mower. I have a couple concerns that I would like to address to keep it running well: 1) It emits smoke when started. 2) When started, the engine doesn't run at a constant speed, it rev's higher and lower while running, though cuts evenly. Any other tips for maintenance assuming it has never had any service or part replacement in its 6 years of life (including oil change). Thanks

Answer
 Hello Brian:

 The Smoke when First Starting isnt a big Worry. Most Mowers after a couple of years tend to Smoke when first Started. The Uneven Idle (up and down) is the Carb. Depending on the Carb on your Engine, it may have Adjustment Screws. I use 10W30 Synthetic Oil and Change it at the Start of every Cutting Season (at least every 25 hrs of Engine Operation). Sharpen the Blade at least 2 times During the Cutting Season. Wash the Grass and Dirt from Under the Frame after each Mowing. Winter Storage: Empty Gas from Tank. Run Engine Until all the gas is out of the Carb. Spray All Linkage and Moveable Parts with WD-40 or other Spray Lubricant. Always make Sure the Blade is Balanced after it is Sharpened. Hope this Helps.

 Good Luck

 Respectfully

 John