Is the engine warm?
Is there oil and/or fuel on the engine?
Can you see any seals leaking?
Is there oil around the rear axles, near the rear wheel?"
Is there oil around the PTO seals?
Are there oil leaks around the output shaft seals gearboxes? (4WD
Is the engine oil at or near the full mark?
Is the front axle dipstick at or near the full mark? (4WD)
Does the oil look clean? Black is ok for diesel engines.
Are there creamy white droplets near the top of the dipstick?
Are all the filters U.S. made?
Is the air filter intact?
Does the air filter have any tears or holes in it?
Is the fuel filter clean?
Is the fan belt tight and in good shape?
Does the air inlet tube have any cracks or holes in it?
Is the water in the radiator dark green? This is a good thing.
Does the radiator water have a milky looking scum to it?
Is there flaking or discolored paint around the radiator cap?
Is there moisture along the bottom of the radiator?
Is there any slop in the steering linkages?
Look over the tractor a second time to make sure you didn't miss anything?