TSB: DT–2005-12-08
Date: 10/21/2005
Subject: Automotive Differential and Manual Transmission Oil Drain and Flushing Procedures
Technical Service Bulletin
OBJECTIVE:
To describe the correct differential and manual transmis-
sion oil change procedures for synthetic gear
lubes.
ISSUES:
The use of improper flushing procedures can cause short-
ened oil drain intervals and contamination, increased wear
and foaming. By using proper flushing procedures with
synthetic gear lubes, maximum gear bearing
and oil life can be achieved.
TECHNICAL DISCUSSION:
Operating conditions may cause a buildup of sludge, wa-
ter contamination or wear particle contaminants. Exam-
ples of some of these operating conditions are:
• Rapid fluctuations in operating temperatures,
high speeds or heavy loads, or shock loading.
• Moisture caused by condensation, spray, or sub-
mersion of the gear case in water will emulsify
the oil and water and degrade the oil..
• Dirty or dusty environments require more fre-
quent lube changes based on increased contami-
nant levels.
• Frequent start-ups and shut-downs
• Towing
• Overloading.
In order to determine if a flush is needed, drain the gear
lube from the transmission or differential when it is still
warm and observe the condition of the oil. If the gear oil
is dark in color, is milky in color, smells burned, has
thickened up, or if particle contamination can be seen,
flushing is suggested. Flush with the synthetic oil product
you’ve chosen to run in your vehicle. Fill to the normal
level and run in a No-Load condition for 15 minutes.
Drain out flush oil, clean any magnets and refill with the
correct synthetic product.
Do not use solvents to flush transmissions or differentials.
Solvents can have the following negative effects on gears
and bearings in differentials and transmissions:.
• Foaming – Residual solvent such as, chlorinated
solvents or solvent-type flushing compounds
used to wash out the gearbox may cause foam-
ing.
• Rust – Gears, bearings and internal parts if left
dry and free of oil, can start rusting in a very
short period of time after they are washed down
with solvents.
• Viscosity Loss – The presence of even a very
small amount of solvent-type flushing compound
can reduce the viscosity of oils.
Make sure the drain and fill plugs are clean when opened
and closed. This will assure a clean and uncontaminated
oil change.
RECOMMENDATIONS:
When necessary use the change and flush procedures ex-
plained in the Technical discussion section in conjunction
with the proper Synthetic Gear Lubes to insure
the maximum manual transmission or differential oil and
component service life.
Courtesy of GotEngines.com @ 866-320-1182
