RE: Stopping Oil leaks

["Michael Liu" <mliu@domain.elided>]

> John Justus asked about oil system leak stoppers:
>
> > I was in the autoparts store the other day, and saw a bottle
> > of stuff that was said to stop oil leaks.  As it was about as
> > viscous as water, I wondered how it could do anything. (Being
> > of the old STP school of thought that a thicker oil doesn't
> > leak or burn.)
> >
> > Does anyone have any idea how this stuff is reputed to work?
> > Does it hit air and harden?
>
> From: Bob Rice
>
> Well, John, I don't know how well they work, but you will never
> find me putting any of that stuff into an engine of mine -- at
> least not if I intend to keep it running for long. Consider that
> if a product is capable of stopping oil from flowing through a
> hole to the outside world, that it can also stop oil from flowing
> through holes to the _inside_ of the engine.

John and Bob,

This stuff is designed to help prevent leaks around oil seals and rubber
gaskets. It works by softening and swelling the old rubber (which has a
tendency to harden and deform over time). The additive itself does not in
any way harden or plug holes. And while it may or may not help with your
leaky engine, it should never cause oil starvation by plugging oil passages.
Note that I am not advocating or recommending the stuff; in fact, I've never
used such a product. But that is how they (are supposed to) work.

Regarding the "old STP school of thought" that thick oil doesn't leak, take
a look at your transmission or differential. See any oil leaks? Many
cars--if not most--will have some oil leakage from a casing flange or from
around a seal. Now ask yourself the following question: Will the oil in my
crankcase ever get as thick as 80W/90 gear oil? If it does, be prepared to
buy a new engine soon. The best oil for your engine is the one recommended
by the auto manufacturer (they engineered the car so they should know,
right?). Using a thicker oil may slow down the leak, but it won't stop it.
In the meantime, you'll be doing significant damage to your engine.

> Buying replacement oil is a lot cheaper than a replacement
> engine.

Or better yet, roll up your sleeves, break out the tools, and rebuild that
puppy! That's half the joy of owning these fine pieces of Italian kinetic
art. And just think how much cleaner the environment will be without yet
another car dumping a quart of oil a week on the ground.

Just one word of advice: if you do decide to undertake a rebuild, stay away
from those damn Spider trunnion bushings!  :P

> My two pennies.

I'll see your two pennies and raise you a penny.  ;)

Regards,

Michael Liu
San Francisco, CA
'90 Alfa Romeo Spider Veloce
'69 FIAT 124 Spider

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