code:
Vehicle: 2003 GMC Envoy
Engine: 4.2L 6-cylinder
Miles on Vehicle: 31,195
Miles On Oil: ~3,200
Oil: Mobil 1 5W-30 SS
Filter: Mobil 1
Oil in use from mid-September 2003 through 11/12/03
Measured Average
Aluminum 3 4
Chromium 2 1
Iron 13 52
Copper 9 14
Lead 1 2
Tin 0 2
Molybdenum 11 41
Nickel 0 0
Manganese 0 1
Silver 0 0
Titanium 0 0
Potassium 0 1
Boron 13 40
Silicon 51 12
Sodium 3 7
Calcium 1942 1933
Magnesium 68 377
Phosphorus 965 745
Zinc 1098 912
Barium 0 1
SUS Vis @ 210F 62.0 54-61
Flashpoint 385 >365
Fuel%
Antifreeze% 0 0.0
Water% 0.0 0.0
Insoulbles% 0.2
TBN Ordered, but not reported.
Analysis:
The only question we have on this initial oil
sample from your GM 4.2L engine is, where did all
the silicon come from? These types of GM engines
average 12 ppm silicon. If the 51 ppm found in
this sample were abrasive dirt, it would have a
serious effect on bearing wear. With all the
metals reading low, easily better than average,
we thiink the silicon is from a silicone product
like an additive or sealer material. Other than
the high silicon, this is the perfect analysis
for your engine after running the oil 3,200
miles. Try 5,000 miles next sample. Wear will
still read okay.
My comments:
This vehicle has a 7-quart capacity, which seems
pretty huge to me. Also, the dealer recently had
to drop the oil pan, before this OCI, in order to
replace the front differential casing. Maybe
they put in a new gasket or something which
contributed to the elevated silicon? Discuss.
