Testing and Adjusting Adhere to the following warnings when performing any tests or adjustments while the engine is running. Engine Oil Viscosity Recommendation NOTE : In normal case, the recommended engine oil for G643(E) engine is SAE 10W - 30. But, if the excessive valve noise occurs up to five minutes after a cold start and if the maximum ambient temperature is lower than 10°C (50°F), it is recommended to change engine oil to SAE 5W - 30 for that application. Synthetic Oils Synthetic engine oils are not recommended for use in G643(E) Engine. Synthetics may offer advantages in cold-temperature pumpability and high- temperature oxidation resistance.
However, synthetic oils have not proven to provide operational or economic benefits over conventional petroleum-based oils in G643(E) Engine. Their use does not permit the extension of oil change intervals. Lubrication System Problems One of the problems in the list that follows will generally be an indication of a problem in the lubrication system for the engine. Too much oil consumption. Low oil pressure. High oil pressure. Too much component wear. W ARN I N G Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury. W ARN I N G Exhaust fumes contain carbon monoxide (CO) which can cause personal injury or death.
Start and operate the engine in a well ventilated area only. In an enclosed area, vent the exhaust to the outside. Engine Oil Engine Oil Recommendation The following oil specifications provide the guidelines for the selection of commercial products : Use gasoline engine oil. Recommended API service classification is class SJ grade. NOTICE Failure to follow the oil recommendations can cause shortened engine life due to carbon deposits or excessive wear. Prior to changing oil, select an oil based on the prevailing daytime temperature in the area in which the engine is operated. The chart in figure is a guide to selection the proper crankcase oil. IMPORTANT :
Oils containing “solid” additives, non- detergent oils, or low-quality oils are not recommended for use in G643(E) Engine. G643 (E) Service Manual Chapter 3. Engine Mechanical System 58