RE: Oil Change Interval & Synthetics Here We Go Again... Long Post

["Marv De Beque" <debequem@xxxxxxxxxx>]

I know this thread has been beaten to death on the PorscheList and probably
here as well, but there are some important considerations about oil and its
change intervals.  This is what I know...

Frequency Factors:

This is dependent on a number of factors.  First, your car.  If it is
turbocharged, then you will experience more heat.  Synthetics offer
advantages owing to their better resistance to breakdown at high
temperatures.

Track use will push the car harder and increase the oil breakdown and acid
accumulation.  This can accelerate oil change intervals.

Type of commuting is a major factor.  High speed highway driving is far less
stressful than stop and go city driving.  In fact, city driving is
considered the "severe" category right up there with spirited street driving
or towing.  Short commuter hops also bump you into the "severe" category if
you fail to get the oil up to temperature for a long enough period.

Climate will impact change intervals.  Extreme heat or cold is harder on car
and oil.

Which Should I use, Synthetic or Standard?:

We all like to take care of our babies, so more seems better.  In fact, it
is really cheap insurance when you consider the alternatives.  If you race,
have a turbocharged car, or run in the severe category of driving, consider
synthetic.  For the rest of us, the standard high quality Carbonaceous Punch
is just fine.

For those of you that have high miles and are thinking of switching to
synthetic oil, you may experience oil leaking after the change.  It seems
that aging seals and gaskets rely on the accumulation of tiny deposits and
perhaps some conditioning of the seals themselves to keep seepage to a
minimum.  Synthetic will wash out those deposits and has been know to cause
sudden leaks (been there, done that).  The cure is to replace offending
seals and gaskets and you are good to go.

When Do I Do The Change Interval?:

I am biased to the 3500 mile rule.  I apply this to both synthetic and
Carbonaceous Punch.  While synthetic has a longer breakdown life, all oils
are plagued by combustion by-products generated in the engine.  I believe
synthetics can handle this better, but the majority of benefits enjoyed by
synthetics are quality control in hydrocarbon chain length.  To my knowledge
there are no secrete ingredients added that conventional oils don't already
have to combat by-products.

The by-product problem is confounded by older cars with excessive blow-by
and high performance engines running under severe category conditions.

Additionally, the acid by-product build up in your engine should be changed
as a function of time, even if you rum low miles per year.  You don't need
those acids sitting on useful engine parts.  Stored cars should have the oil
changed when stored and NOT restarted until brought out of storage.  The
exclusion is if you regularly start a stored car, then it should be allowed
to run with the oil at operating temperature for a spell.

If 3500 miles seems excessive, then consider the numbers.  My car uses 12
quarts of oil.  If I replace it three times a year, then that is 36 quarts
of oil.  For synthetic, that costs me about $150.00 a year.  Add three
filters, and I raise the bar to $175.00 every year.  That comes out to far
less than the cost of one six pack of quality German beer each week.

If I use standard oil, it cost me less than $75.00 per year (includes
filters).

Since your cars use almost half that amount of oil in the engine, then your
costs will be substantially lower.  As an example, my girlfriend's 325i
would use only 7 quarts each change or 21 quarts a year.  That comes out to
$84.00 plus filters or $110.00 total.

If you try to stretch your synthetic oil change to even once a year, then
your savings would be just under $120.00 a year if you own a 911 and if you
own a 325i, you save $70.00 over the course of one year (using synthetic)!

Now, if you use Carbonaceous Punch, those savings are meaningless noise.

Consider most shops are getting almost $65.00 per hour for repairs, it seems
like very good insurance for your motor to change oil more frequently.  How
many years, at $70 per year, would you need to save to replace your motor?

Despite manufacture recommendations, I can't justify the savings in my mind.
Additionally, those extra changes can be used to inspect your car for
trouble on the rise.

Additives:

In a word, DON'T.  If those snake oils were really beneficial, oil companies
would be using them already.  Competition among oil companies has pushed
oils to the limit of technology.  Large fleets like those owned by state and
local governments reap giant savings with the best oil, so the competition
is sharp and we reap the rewards.  Snake oils just prey on our desires to do
our engines the best we can.  Don't buy it.

Products that contain PTFE actually produce hydrofluoric acid in the oil.
This is then flushed out the exhaust where it slowly eats out the catalytic
converter, or the oil filter is clogged by the Teflon particles (that's what
filters do).

Sorry about the blathering...

Marv
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debequem@domain.elided
http://home.att.net/~mdebeque/index.html

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