Sending fluid samples from the engine, transmission, and hydraulic reservoirs to a laboratory before buying a used tractor is a wise precaution. Oil analysis detects trace microscopic metals that indicate premature bearing, piston ring, or gear wear. This low-cost diagnostic test provides definitive scientific evidence of internal component health that simple visual checks cannot reveal. https://mysportsgo.com/Blog/76272/identify-used-tractors-without-serial-numbers-cast-codes