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Oil Analysis at 7500 miles
Recently there was some discussion about whether to change the oil prior
to the first scheduled change at 7500 miles. I've included the
following post that may be of some help. I came across it on the
Corrado list, and I believe it originated from someone on the GTI list.
Bob R.
_______
OK list members,
We have had many discussions about when to have the first oil change and
what VW puts in there for "break-in" oil. I opted to wait for 7500
miles
on my '96 (which was the VW recommendation). I saved some of the oil
and
sent it the Cleveland Technical Center labs for analysis to see how it
was
holding up. Oil analysis can be a great way to check for problems in an
engine and to see if your oil change interval is OK. I also thought it
might provide some insight into the "recipe" VW uses for break in. Of
course, I don't have any baseline info to compare this to... it would
have
been great if I had drained a little when I took delivery and had it
analysed, but no such luck.
So, the results at 7584 miles are (all values in parts per million
[ppm],
unless otherwise stated):
Iron 44
Chromium 3
Lead 4
Copper 31
Tin 0
Aluminum 16
Nickel 0
Silver 0
Manganese 0
Silicon 11
Boron 3
Sodium 255
Magnesium 33
Calcium 2845
Barium 6
Phosphorus 680
Zinc 1030
Molybdenum 1
Titanium 0
Vanadium 0
Potassium 0
Flash Point not evaluated
Fuel (% vol) <1
Viscosity at 100 degrees C (cSt) 12.28
Water (% vol) 0
Solids (% vol) 0.1
Glycol Negative
Oxid 11.0
Nitr 13.0
Interpreting these results is open to discussion, but the folks in
Cleveland are the folks who make Amsoil products... which includes very
good synthetic oils. They reported that the results indicate no
corrective
action required. In other words, the oil was still fine and didn't
actually need changing. This is nice to know... clearly waiting for the
full 7500 mile change interval does not subject your engine to oil
failure.
Some other things that can be gleaned from the info listed on the back
of
the report are: The metals Fe, Cr, Pb, Cu, Sn (tin), Al, Ni, Ag
(silver),
Mn, Ti, and V can all be derived from wear of various engine parts
(cylinders, gears, rings, valves, etc. Pb is also a common gasoline
additive (although not when you use unleaded, obviously). None of those
values are very high in my oil test. Existence of wear is usually best
indicated by an increase in these numbers over past tests--so if you
really
wanted to know you'd have to check the same oil after several thousand
miles I guess.
Si, B, Na (sodium) and K (potassium) are contaminants that can be
indicators of either external or internal contamintation. For example:
Silicon can be used to track the level of airborne dirt and abrasive in
the
oil... but is also sometimes used as an antifoam agent. Boron, sodium
and
potassium are present in most permanent anti-freeze systems and cooling
system corrosion inhibitors... sometimes also used as additives.
Mg, Ca, and Ba are used as dispersents and/or detergent additives by
some
oil manufacturers. Phosphorus, zinc and molybdenum are common anti-wear
additives.
The viscosity measurement corresponds to an SAE grade of nearly 40
(9.30
cSt is grade 30 and 12.50 cSt is grade 40... mine was 12.28, which is
grade
39.9 if the scale is linear).
All-in-all, I wish I could afford to do analyses more frequently, but
they
do cost $8 for the analysis, $5 for the "kit" with the little jar and
postage... not to mention the time to go out and carefully clean off the
filter drain plug so you don't get any contamination in your sample. I
dunno, maybe I'll bite again to track my synthetic oil... but not this
month.
Hope you all find it as interesting as I do.
Ah... if you want to have your own done. You could try calling
Cleveland
Tech at (800) 726-5400. I bought my kit locally, but they may sell them
directly or let you just send it in any new, small nalgene bottle you
can
find.
-
David Elbert
elbert@jhu.edu