Many years ago, a special magazine called Motorcycle Consumer News did a study
on this
claim. Basically, it's a fake claim. DOT has regulations on the amounts of
gear
additives allowed in motor oil. The "special" motorcycle oils are no higher in
Sulfur,
Zinc, or the other metal used to lubricate gears then any other motor oil.
Instead, they
just brag about it, and charge lots more for the bragging.
Don't get all caught up in GL-5 issues for a gearbox though. The hypoid gear
oils (GL-5)
are special. The sliding shear of the differentials ring and pinion gears are
brutal to
oil, and require special protections, hence the GL-5 recommendation normally
given. A
transmission on the other hand, doesn't have these severe shear loads, so they
don't need
GL-5. Many modern gearboxes are capable of running GL-5, making servicing
easier; but it
isn't necessary.
For the most part, a manual transmission will do just fine on motor oil. It
will need to
be changed regularly, say at 30K miles or so. But as long as the oil changes
are done,
it will hold up just fine in there.
Don't forget, the weights for gear oils and motor oils are on a different
scale, so a 90
weight gear oil is roughly equivalent to about a 50 weight engine oil.
Steven Fooshee wrote:
> While I'm on the subject of motorcycle fluids, has anyone given
>consideration
> to using 20W-50 motorcycle oil for the ribcase? One of the points that the
>local
> motorcycle shop explained to me that I have to pay $2.50 a quart for this oil
>is
> that it's specifically formulated for use in gearboxes (bikes share their oil
> Mini-style).
|