Service Manual

Lubricating Oil Contamination ISB, ISBe and QSB (Common Rail [...]
Page 7-48 Section 7 - Lubricating Oil System - Group 07
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Incomplete combustion in the cylinders can result in
unburned fuel draining into the oil pan.
This condition can be caused by a leaking injector or
reduced compression caused by inadequate piston ring
sealing.
An increase in white exhaust smoke during the first start
of the day is a symptom that an injector is leaking.
An injector leak will also cause the engine to run rough
and have low power.
Remove and repair or replace leaking injectors. Refer to
Procedure 006-026 in Section 6.
Perform a compression check to verify piston ring sealing.
Refer to Procedure 014-008 in Section 14.
There is a remote possibility for fuel to drain into the oil
from the diaphragm-type fuel transfer pump.
For this to happen, the diaphragm in the pump will break
and the drain hole will need to be plugged.