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🚗 Seal the deal with K-Seal Ultimate — never let a leak slow your drive!
K-Seal Ultimate is a professional-grade, permanent head gasket and engine block repair fluid that offers 33% more sealing power than regular formulas. It permanently seals leaks up to 0.64mm using ceramic micro-fibres, requires no engine draining or flushing, and is compatible with all coolant types and engine materials. Trusted by mechanics worldwide and independently verified, it provides a cost-effective, long-lasting solution to engine leaks.










| ASIN | B00Q55SV6O |
| Best Sellers Rank | 4,741 in Automotive ( See Top 100 in Automotive ) 64 in Fillers, Adhesives & Sealants |
| Brand | K-Seal |
| Customer Reviews | 3.8 3.8 out of 5 stars (595) |
| Global Trade Identification Number | 05060002968109 |
| Included Components | 1 Bottle |
| Item Shape | Round |
| Item Type Name | Head Gasket Repair |
| Manufacturer | K-Seal International Limited |
| Manufacturer Part Number | KSLST3501 |
| Model Number | KSLST3501 |
| Product Warranty | 1 year manufacturer |
A**R
Worked with heavily modified car, temp fix.
The product works great, had to unfortunately use it on my stage 3 3l a5 diesel. Temporary fix, While while I rebuild the engine, but it worked immediately, I have tried others, steel seal etc. None worked except this, however, I do believe it did damage the thermostat, but I can't say it definitely was this. Recommend.
G**N
Works really well
Works really well. Just make sure you really warm the engine fully. Great item. Fast delivery. Well packaged. Highly recommended 100% good
P**1
This will work for some applications
But in my case it did not work fully. I think it reduced the problem somewhat but I can't dismiss it entirely as I can't be certain what was causing my problem. At the price, it's got to be worth a try.
K**X
Did not work for me
Head gasket started to leak on my Mercedes Sprinter, gasket was not leaking directly but radiator pressurising when engine under heavy load causing water to be expelled through radiator pressure relief cap, (cap tested and found to be in good condition) I purchased a radiator pressure tester to check for leaks and found none, tester would hold pressure over night so came to conclusion that head gasket must be starting to leak under load. Thought I would try Kalimex head gasket sealer as it stated that this was one of the problems it could perminamtley fix, £30 per bottle later I added the Kalimex as per instructions, set off on test drive, 5 miles later water level was low again, product did not work. Am now sending for refund as per guarantee.
M**A
Good
Good
M**A
I just don't know - do I need 2 lots given engine size?
Not sure how many stars to give this?? I have a BMW X5 4.8is V8 Petrol. I am losing water - but only a tiny bit poss 0.25L each week. Slight steam from exhaust when idling but again not much & hard to tell if coolant. No water in oil & no oil in water... I can only imagine it must be a tiny head gasket problem. Mechanic says no leaks. Car still drives like a dream. I have dosed the engine with one of these and given other positive reviews you would think that it would have done the trick? Maybe with the engine size I need 2 lots - however do not want to waste another £24 if it does not do the trick - really stuck - any wisdom on here? also noticed product says money back if it does not work - I wonder how to invoke that if I buy another and no joy? M
M**K
Sealant
Did the job, car back on the road, seams to have sealed the leakse
D**R
worked a treat for me !!
My trusty 1996 Diesel car of 17 years had to be sold due to the stupid and criminal extension of ULEZ (extended outside of the A406, by the London Mayor). Unfortunately the replacement vehicle I bought (it wasn't obvious at first) had a suspect blown head gasket , I thought the slight oil in the coolant was due to lack of maintenance/servicing by the previous owner & the broken seals on the oil cooler - there were no other head failure gasket symptoms . Also a co2 head tester test showed negative to head gasket issues. 6 months after the purchase, the oil management light came on. Diagnostics showed cylinder 2 misfiring. I replaced all the spark plus & ignition coils, the light disappeared for a day , but came back again. My local garage took out the spark plug to cylinder 2 & used some sort of Otoscope to peer into the cylinder and saw coolant in there. He recommended K-seal. I read reviews and results seem to be 50/50, (I presume it depends on the seriousness of the gasket damage, how successful this treatment will be) . But for my Nissan Xtrail 2.5 litre Petrol engine this worked a treat. No vibrating when i started the car, the car ran smoothly. Whether K-Seal would last for a long time, I cant say, I had a road trip planned and wasnt going to risk it, but definitely as a stop gap till i got another car, this worked brilliantly. Its a gamble, but even for the price (£32) I would definitely sue this product again as a stop gab or to get me out of a tricky situation ie getting home rather than being stranded. As for the long term issues with having this in your engine, some say its ok, some say its not great for the cooler system, but for an older car my feeling would be 'why not use it, especially as a stop gab.
R**O
Ho prima messo a livello l'acqua nella vaschetta a motore freddo, ho tolto la quantità d'aqua dalla vaschetta pari al prodotto, ho versato il prodotto nella vaschetta , ho avviato il motore METTENTO LA STUFA A CIRLCOLO ARIA CALDA , ho fatto riscaldare da fermo il motore fino a 80 gradi poi ho circolato per 3/4 km . ho spento e fatto raffreddare 5/6 ore. dopo di che ho usato la vettura regolarmente. IL PRODOTTO HA FUNZIONATO. La vettura è una Fiat stilo SW 140cv Multijet con 450.000 aveva soffiatura alla testata che mi consumava circa 150ml di acqua ogni 100 km (un bel bichiere di acqua) cacciando fumo bianco dalla marmitta. Ora dope Tre giorni ho percorso circa 560 km NON CACCIA FUMO BIANCO NE CONSUMA PIU ACQUA: al momento va benissimo non so quanto duri . comunque ho rimandato la rottamazione!!!
J**Z
Subaru Outback 2.5 l anée 2000, 210.000 km. Elle perdé l’anticongelant par la joint de culasse en grande cantité (odeur, fumée dessous le capot). J’utilisé K-Seal Ultimate et le problème a été corrigé. 3 semaines plus tard il n’y a le moindre symptôme du problème.
R**D
Good product work on my car now .now to gas prblm everthing stop
S**D
La verdad que ha funcionado tenía un poro, le echamos el líquido hicimos 25 km como nos recomendaron y de verdad que lo notamos el coche tiraba mucho mejor, fácil de poner.
T**.
Head gasket and it worked
Trustpilot
2 weeks ago
2 weeks ago