Arrived on site to perform furnace maintenance. Client stated that heater has not been used once this winter because propane smell was occurring in the summertime so gas shut off. Turn gas back on and system ran properly with no propane smell. Found multiple points of concerns within the unit. Indoor blower motor and inducer motor have lost a significant amount of oil which will lead to them locking up or overheating. Indoor blower cabinet has dust and debris buildup. Flame sensor was clean but is oxidized. Filter is a horse hair washable and should be cleaned every month. Discussed full maintenance with Mrs Craft And she stated that they will be selling the house in February so nothing will be done at this time upon departure unit is operational.