No they do not! Many of the world’s largest auto manufacturers
require the use of synthetic motor oils as “factory fill” including Porsche and
Mercedes. Even GM requires it in certain vehicles such as the Corvette.
So what’s going on? Why the stories about the guy who put
synthetic motor oil in his car after having no engine oil leaks running for
perhaps several years using petroleum motor oil. Then all of a sudden he finds
drips after a few weeks. Here’s what’s going on.
Synthetic oil flow more readily than petroleum oil does so if you
have a leak it will tend to leak from it more freely. This however is caused by
an all ready failing seal. Not by the synthetic oil itself. ;
Petroleum motor oils are notorious for forming what's know as a "false
seal" Varnish and crud will build up around a failing seal over time and
help keep a more viscous petroleum oil from leaking. Synthetic oils that are
highly detergent will clean off the build up and expose the all ready failing
seal. There's your leak! ;
For this reason I suggest that synthetic oil's only be used in mechanically
sound engines. If you have a leaking seal replace it prior to installing
synthetic motor oil. ;
I have also seen many cases where older engines are starting to seep oil
because some motor oils have poor long term seal compatibility. Exposure to
these low grade oils causes the seals to harden and seal poorly. ;
All motor oil, synthetic and petroleum alike contain chemicals as part of the
additives that are added to the oil that are there to keep engine seals pliable
and to cause mild swelling so the seal works properly. Some oils are better at
this function then others. Another reason cheap motor oil is no bargain in the
long run! ;
The additive's in Amsoil’s synthetic motor oils are so good at conditioning
engine seals that there have been many cases where engines with slight oil
seeps sealed back up after a few thousand miles of driving. That being said if
the seal is shot all you can do is get it fixed; no oil will fix it, synthetic
Included.
Amsoil Inc developed the first full synthetic motor oil in 1972 to
achieve American Petroleum Institute certification and today is considered the
world leader in synthetic motor oils and lubrication.
By Larry Crider, Lubrication Specialist