Oil Consumption

[Escoses@aol.com]

>From time to time there have been posting regarding regarding the thirst (or
lack of it) for oil of the engines in those cars that serve our masochistic
tendencies. This morning I was in my favourite money pit (as in throw it in)
and was playing around with their Alldata computer; doing my best not to
think how much today's visit was going to cost me. A cheap visit, new control
arm bushings and a new ISV (I guess you can only clean it so much before it
finally gives out - six months is about the limit).

Anyhow, I came across the following TSB which might be of interest to all
fellow masochists:

>Group: 17
>Number: 94-02
>Date: August 1, 1994
>Subject: Oil Consumption, Explanation
>Models: All Models, All Model Years

>Engine oil serves many purposes in the internal combustion engine
(surprise!)
>*  A dependable lubricant for all sliding and bearing surfaces.
>*  Acts as a coolant and dissipates heat.
>*  Ensures cleanliness through detergent action and filtration.
>Even an efficiently running engine consumes oil or it would quickly wear
out. All of the >engine friction surfaces are cushioned by a thin film of
oil. The upper piston ring >(compression ring) for example, is lubricated by
a thin film of oil deposited on the >cylinder wall. This microscopic film is
burned away during combustion. Although very >little oil is consumeed per
stroke, over long distances small amounts can add up to >whole quarts of oil.
For this reason the oil level must be checked regularly.

>The amount of oil an engine consumes depends on how the vehicle is driven.
This is >especially noticeable during the first 7500 miles when an engine is
being broken in and >the internal components are seating.

>Some factors affecting oil consumption are: the ambient temperature, engine
size, >quality and viscosity of the oil and the way the vehicle is driven.

>When a vehicle is driven at highway speeds, unburned fuel, by-products of
>combustion, condensation and contaminants evaporate through the crankcase
vent >system and are consumed via normal combustion. A vehicle driven for
short trips >without fully warming up the engine or in cold weather may not
appear to consume any >oil because unburned fuel, by-products of combustion,
condensation or other >contaminants will mix with the oil and give the
appearance that no oil is being >consumed. In some cases, the added
contaminants will even cause the oil level to rise >significantly.

>The best conditions under which to check the oil level are with a warm
engine on a >level surface. When checking the level a warm engine, it is
recommended that the >engine sit for five to ten minutes with the ignition
switched off. This allows the >circulated oil to drain back into the oil pan
for accurate reading.

>Always use the correct API and SAE rated oils for the specific driving and
>environmental conditions the vehicle will experience, as recommended in the
Audi >Owners Manual.

>Always change the oil at the intervals specified in the Audi Maintenance
Manual.

They very carefully don't tell you what might be considered normal
consumption: IE 1/2 Quart per 1,000 miles? 2,000 miles? 3,000 miles? My guess
is that anything upto a quart every 3,500 miles under high speed Interstate
driving conditions in summer is probably OK.

What is true is that you are not going to have an engine very long that DOES
NOT CONSUME ANY OIL AT ALL.

Have fun,

Graham