Date: Thu, 31 Jan 2002 20:42:01 -0600
Reply-To: Stan Wilder <wilden1@JUNO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Re: Synthetic oils
Content-Type: text/plain; charset=us-ascii
What does my oil actually do?
An engine oil's job is primarily to stop all the metal surfaces in your
engine from
grinding together and tearing themselves apart (and that's the last thing
we'd
want!). But it also has to dissipate the heat generated from this
friction too. It also
transfers heat away from the combustion cycle. Another function is that a
good
engine oil must be able to hold in suspension the nasty by-products of
fuel
combustion, such as silica (silicon oxide) and acids, whilst also
cleaning the engine of
such nasties. And it must do all of these things under tremendous heat
and pressure
without succombing to fatigue or black death, the ultimate engine
destroyer.
What the heck is Black Death?
Black death first appeared in the early 80's when a horrible sticky black
substance
was found to be the cause of many engine seizures in Europe. Many engines
were
affected but Ford and Vauxhall (GM) suffered the most. Faster roads,
higher
underbonnet temperatures, tighter engineering tolerances and overworked
engine
oils were the cause. The oils just couldn't handle it and changed their
chemical
makeup under pressure into a sort of tar-like glue. This blocked all the
oil channels in
the engines, starved them of lubrication and caused them to seize. This
could all
happen in a matter of minutes. This was the catalyst for the production
of newer
higher quality oils, many of them man-made rather than mineral-based.
Mineral or synthetic?
Mineral oils are based on oil that comes from dear old Mother Earth which
has been
refined. Synthetic oils have minimal mineral oil content and are entirely
concocted
by chemists wearing white lab coats in oil company laboratories. For more
info, see
the section on synthetics further down the page. The only other type is
semi-
synthetic, sometimes called premium, which is a blend of the two. It is
safe to mix
the different types, but it's wiser to switch completely to a new type
rather than
mixing.
A couple of words of warning:
? If you've been driving around with mineral oil in your engine for
years, don't
switch to synthetic oil without preparation. Synthetic oils have been
known to
dislodge the baked-on deposits from mineral oils and leave them floating
around your engine - not good. I learned this lesson the hard way! It's
wise to
use a flushing oil first.
? If you do decide to change, only go up the scale. If you've been
running
around on synthetic, don't change down to a mineral-based oil - your
engine
might not be able to cope with the degradation in lubrication.
Consequently, if
you've been using mineral oil, try a semi or a full synthetic oil. By
degradation, I'm speaking of the wear tolerances that an engine develops
based on the oil that it's using. Thicker mineral oils mean thicker
layers of oil
coating the moving parts (by microns though). Switching to a thinner
synthetic oil can cause piston rings to leak and in some very rare cases,
piston slap or crank vibration.
? Gaskets and seals! With the makeup of sythetic oils being different
from
mineral oils, mineral-oil-soaked gaskets and seals have been known to
leak
when exposed to synthetic oils. Perhaps not that common an occurance, but
worth bearing in mind nevertheless.
Synthetics
Synthetic oils are derived from many sources, but the most popular and
stable are
those derived from polyol ester bases. As I mentioned above, these are
typically
concocted by intelligent blokes in white lab coats. These chaps break
apart the
molecules that make up a variety of substances, like vegetable and animal
oils, and
then recombine the individual atoms that make up those molecules to build
new,
synthetic molecules. This process allows the chemists to actually "fine
tune" the
molecules as they build them. Clever stuff.
Now I mentioned above that the most stable bases are polyol-ester (not
polyester,
you fool). When I say 'stable' I mean 'less likely to react adversely
with other
compounds.' Synthetic oil bases tend not to contain reactive carbon atoms
for this
reason. Reactive carbon has a tendancy to combine with oxygen creating an
acid. As
you can imagine, in an oil, this would be A Bad Thing. So think of
synthetic oils as
custom-built oils. They're designed to do the job efficiently but without
any of the
excess baggage that can accompany mineral based oils.
Flushing oils
These are special compound oils that are very, very thin. They almost
have the
consistency of tap water when cold as well as hot. Typically they are
0W/20 oils.
Don't ever drive with these oils in the engine - it won't last. Their
purpose is for
cleaning out all the gunk which builds up inside an engine. Note that
Mobil1 0W40 is
okay, because the '40' denotes that it's actually thick enough at
temperature to
work. 0W20 just doesn't get that viscous! To use them, drain your engine
of all it's
oil, but leave the old oil filter in place. Next fill it up with flushing
oil and run it at a
fast idle for about 20 minutes. Finally, drain all this off (and marvel
at the crap that
comes out with it), replace the oil filter, refill with a good synthetic
oil and voila!
Clean engine.
Of course, like most things nowadays, there's a condition attached when
using
flushing oils. In an old engine you really don't want to remove all the
deposits. Some
of these deposits help seal rings, lifters and even some of the flanges
between the
heads, covers, pan and the block, where the gaskets are thin. I have
heard of
engines with over 280,000km that worked fine, but when flushed it failed
in a month
because the blow-by past the scraper ring(now really clean)contaminated
the oil and
screwed the rod bearings.
So what should I buy?
Quality Counts! It doesn't matter what sort of fancy marketing goes into
an engine
oil, how many naked babes smear it all over their bodies, how bright and
colourful
the packaging is, it's what's written on the packaging which counts.
Specifications
and approvals are everything. There are two established testing bodies.
The API
(American Petroleum Institute), and the European counterpart, the ACEA
(Association des Constructeurs Europeens d'Automobiles - which was the
CCMC).
You've probably never heard of either of them, but their stamp of
approval will be
seen on the side of every reputable can of engine oil.
On Thu, 31 Jan 2002 17:59:09 -0800 developtrust <developtrust@HOME.COM>
writes:
> Perhaps this is in the archives but does anyone know from what are
> the
> synthetic oils made?
>
> Having just changed to Mobil one engine oil I see (actually feel)
> that it is
> much more slippery and seems more difficult to clean off my hands
> when
> washing with soap. I had to wash my hands three times as I forgot to
> wear
> rubber gloves and still had some oily residue.
>
> William Polowniak
> 1989 Vanagon GL
> 1988 Mercedes 300 SE
>
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