|Synthetic oils have been
available for almost 30 years and a number of
inaccurate myths have developed during this time.
Some areas of misunderstanding are clarified below,
including manufacturer requirements for using
synthetics, how to switch from conventional to
synthetic oil and the effects of synthetics on an
Myth 1: Synthetic oils are too thin to stay in the
This is not true. In order for a lubricant to be
classified in any SAE grade (10W-30, 10W-40, etc.),
it has to meet the viscosity guidelines, or
thickness, specified by the vehicle manufacturer.
Myth 2: Synthetic
oils will void manufacturers’ warranties.
Synthetic oils will not void manufacturer
warranties. They are formulated with the
requirements of the auto manufacturers in mind, and
so if they’re used in accordance with the owner’s
manual, synthetic oils will not void any of the
warranties. The only exception is that full
synthetic oils should not be used in Mazda rotary
engines, which have unique and specific lubrication
requirements. Always check the vehicle owner’s
Myth 3: You can’t
switch between conventional oil and synthetic oil.
Switching between synthetic and conventional oil
will not cause any harm to engines. Synthetic oils
and conventional oils are formulated to help protect
your emission system, including oxygen sensors and
4: Synthetic oil will make seals leak.
If an older engine’s seals do not leak with
conventional oil, they will not leak after switching
to synthetic oil. Synthetic oils do not damage
engine seals in an engine of any age.
Myth 5: Synthetic
oil cannot be used to “break in” a rebuilt engine.
In a rebuilt engine, a certain amount of controlled
wear can be expected to occur to allow piston rings
to “seat” and the engine to “break in.” Synthetic
oil may be used for the “break-in” period and
throughout the life of the engine.
Synthetic base oils combined with a strong additive
package allow synthetic oils to perform better than
conventional motor oils under virtually all