Another procedure which requires changing the main and connecting rod bearings for new ones is the engine overhaul, but the old bearings must be kept as well since they can reveal much information about the state of the engine. Since bearing failure can be attributed to many causes such as inadequate lubrication, foreign particles, excessive loads and corrosion, one has to ensure these causes are erased before the next cycle of use of the bearings by the need to reassemble them. When inspecting the bearings they should be placed out from where they are used and arranged to be clean in order to match any typical flaws with the crankshaft journal. Bearing contaminants may be introduced at assembly or through the filters, and from the machining operation may be partially embedded into the bearing, while larger ones may score the journal. To avoid such failures, cleaning of all the parts and periodic replacing of the oil and filter should be done. Such consequences may arise from insufficient supply of lubricant due to causes such as excessive temperature, excessive loading, loss of oil or obstructions to oil flow and can cause matters such as total removal of the bearing material. Other driving activity also affects bearing or oil, for example, when low RPM is engaged at low speed, this puts crazy loads that force out oil, or alternatively, very short duration trips that do not produce enough heat ending up in corrosion. Also, bearings can fail due to inadequate application of the oil through installation or other surfaces creating high spots.