I have often tried the additive (some of the American ones although more expensive seem best).
A couple of old vehicles stopped leaking within a few days driving never to be a problem again. Others it did SFA. If the seal is shrunk from age or a smooth groove worn in the shaft - good chance. If it is torn broken or rough bearing surface - no good. You will not know until you try.
I think if you have a fairly new vehicle it is not going to work as the seal is more likely to be damaged than shrunk or a groove worn in the shaft as it works by swelling the seal and giving it back its flexibility.
In your case I would certainly give it a go. It is not going to hurt anything and $30 might save many hours of labour pulling gearboxes. Give it time, might take 1,000km.
This one has definitely worked on a couple of army jeeps and miraculously on a 1915 Willys Overland.
Here I go off topic again...The only magic oil formula I've ever used was "diffshutthef*kup" which actually worked amazing well on a noisy diff! I've tried a bit of things like "power steering stop leak" and various other desperation things, but not much joy.
That said, I'd like to try out the "decarbonser" that is still advertised as a wonder product for fixing your fumey old truck.. I have my doubts tho, and I'm too tight to buy some cos I know it will probably do bugger all..
BUT- bars leaks. And chemiweld. Now theres two products that DO work, cos' I've had a fair crack at both in various busted rally cars and other old junk... Miracle products, I tells ya.....
The following user(s) said Thank You: Lang, PaulFH
I'm with Hayseed and MrsmackPaul on this one despite Lang's good experience. I worry about what the additive will do to bearings and tiny oilways, oil filters and goodness knows what else. This is only my gut feeling as I have no scientific knowledge of these things.
I have my shoulder to the wheel,
my nose to the grindstone,
I've put my best foot forward,
I've put my back into it,
I'm gritting my teeth,
My point is it costs $30 to try the magic brew. It does work in certain circumstances. Rislone and many others have been around for 100 years and you can not stay in business if your stuff does not work.
I don't think it is helpful for a bloke doing up an old truck with limited knowledge or experience and without the equipment to carry out the job easily to be told "just fix it" as though it is a 5 minute job or he has an Interstate B-Double waiting to head off on its next paying trip in a commercial operation.
Sensible philosophy says start on the easy stuff first.
How bad is the leak? A show truck could go for 20 years, or until the repair funds are available, with a rear main bearing leak of a minor nature.