Isuzu 4BG1 Instruction Manual page 34

3) Also check the sample oil on the dipstick for fouling and
degrees of viscosity.
NOTICE: Oil level check must be made ten or twenty minutes later
after the engine has been stopped. When the oil level
check is necessary while the engine is running, stop the
engine and keep it stationary ten or twenty minutes until
the oil thoroughly flows down to the crankcase.
4) Oil is poured through the oil filler at the front of the cylinder
head cover.
A certain period of time is required before the engine oil
completely flows down from the oil filler to the crankcase.
Check the oil level ten or twenty minutes after oil
replenishment.
NOTICE: If the engine oil is splashed on the fan drive belt, it causes
belt slipage or slackness; therefore, take care to avoid it.
Fig. 10
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