Leak stopper oil addative - pros and cons

[Knot It]

Can.t find anything on this subject in the search, and not much on the net about use specifically in a marine engine. I did find a couple of products which seem to be safe for marine use:
http://lucasoil.com/products/engine-oil-additives/engine-oil-stop-leak
http://newtintl.homestead.com/seallube.html
http://www.summitracing.com/parts/atp-at205/reviews/?sortReviews=Newest

Whats your opinion? Anyone used any of these products or something similar?

 

[northern]

Long ago people used to put saw dust in engines to make them better for a few days.

 

[Chris Nowell]

These products may provide temporary fixes by causing the seals to swell and actually seal better. IMHO though, if seals are leaking, the best fix is to replace them.

 

[paulswagelock]

All of these products contain seal swellers, and can help depending on the nature of the leak.
you could also use a high mileage oil, they contain seal swelling agents as well.
problem with all of these is the benefits will go away after a while once they are out of the crankcase.

 

[hottoddie]

I have been told by several experienced mechanics that the Lucas additive will help. I use them but only for the added protection in my 1986 flat tappet engines. If they help prevent oil leaks all the better.

 

[BillK2632]

Have you got a leak? My opinion on the additives and high mileage oil is they don't hurt, but don't help much either. The only real fix is to replace the seal or gasket. That said, my 4.3 started leaking a little oil around the timing cover (common GM 4.3 issue) I was able to tighten the oil pan and stop 90% of it. I can't see how any additive would fix that leak. - the real fix is replacing the oil pan gasket - easy in a car, a big deal in a boat.