STP Radiator Sealer

[aneesh84]

I had been losing antifreeze from my C5 for quite some time at a slow but constant rate. It seemed to be coming out of water pump gasket. The pump was replaced only 3 years ago.

A mechanic advised me to try STP Radiator Sealer. I was initially hesitant since I had read warnings about it plugging the heater matrix. Nevertheless I tried this one.

And its been more than a month and I must say I am very pleasantly surprised. The leaking has stopped, and my heater works perfectly. I dont know about any long term implications, but as of now I am very satisfied with the product.

Would like to hear experiences from others if they tried this or similar products.

[van ordinaire]

Lots of dire warnings about these products (as with any snake oil) even the GM factory fitted Barr's Leaks pellets! However, my friendly local mechanic said he'd only use Wynn's, as the only such product known to work. Can't speak for it myself, although may be able to later as found some in a cupboard which will probably go in the red Cherokee, which loses a little coolant although has no apparent leeks.

[Stickyfinger]

The "problem" with sealers is for cars with the very fine water/oil coolers and/or the equally troublesome gearbox oil/water heat exchangers.

[aneesh84]

The "problem" with sealers is for cars with the very fine water/oil coolers and/or the equally troublesome gearbox oil/water heat exchangers.

Which cars would that include? The C5?

[Stickyfinger]

Yes, and Xantia. Some members report blockages in their cabin heater as well.

[Hell Razor5543]

As far as I can recall, the only sealer that is recommended is Forté Stop Leak. Valeo (who are an OEM) require you to use it (for warranty purposes) if you are replacing the heater matrix.

[Stickyfinger]

That is correct James

[wheeler]

I have used K seal many times with great success.

[Subsonicnat]

Iwas Always led to believe these were a Get you Home Solution,, Not For a Permanant Solution.. I believe you are always asking for trouble if trying to use it as a permanant Fix.
Heaters are very prone to block, Hence overheating and should the worst happen blown head gasket and worse still,Bent conrods..
Get you home,Yes,, Stop gap, Yes..
Solution:: Fix it properly,, Will, work out cheaper in the Long Run.

[aneesh84]

Iwas Always led to believe these were a Get you Home Solution,, Not For a Permanant Solution.. I believe you are always asking for trouble if trying to use it as a permanant Fix.
Heaters are very prone to block, Hence overheating and should the worst happen blown head gasket and worse still,Bent conrods..
Get you home,Yes,, Stop gap, Yes..
Solution:: Fix it properly,, Will, work out cheaper in the Long Run.

There are warnings like you mention all over. But these solutions could have evolved over the years. For me STP radiator sealer has worked fantastically over the last two months, as for many others. So I created this thread to share real experiences not hearsay. I have not seen one post from someone who used these sealers in recent years and had an otherwise clean system and faced blockage issues.

[van ordinaire]

I have used K seal many times with great success.

That's a very worrying statement - on several levels!

[aneesh84]

I have used K seal many times with great success.

That's a very worrying statement - on several levels!

LOL! I am sure he means "used on different cars". I guess we should be open to hacks and improvised solutions, sometimes they are well worth the cost and effort they save.

[van ordinaire]

Even if you're right - he's been very unlucky!

No problem with improvisation - but K-seal's touted as a permanent repair, whereas it's known to have caused permanent damage!

[aneesh84]

Even if you're right - he's been very unlucky!

No problem with improvisation - but K-seal's touted as a permanent repair, whereas it's known to have caused permanent damage!

The customer reviews seem quite positive: https://www.amazon.com/K-Seal-ST5501-Pu ... merReviews

[van ordinaire]

They do indeed, but I can vouch for the fact it's about as useful as Holts Radseal & evidence of its use will lead to sucking of teeth by any mechanic, dire warnings/horrific anecdotes &, possibly, a refusal to work on the vehicle.