Question 1

Can this be used on a valve cover gasket to get a better seal?

Accepted Answer

Yes.  It is better than OEM gaskets in that it conforms to any warpage, dents, dings, & other incongruities, whereas OEM gaskets are designed for factory new, perfect valve covers without flaws.  Withstands 700 degrees.

Question 2

Can I use this product to seal several non-moving parts of a wood burning stove instead of the standard gasketing material?

Accepted Answer

This gasketting goop is absolutely incredible for sealing wood stove parts.  I’d certainly never use it on the fire box.  But it can and will hold to moving parts in high temperatures.  It lasts for several years on one application.

Question 3

can I use this to seal radiator tubes to a heat exchanger in my gas furnace? Gaskets no longer available for it.

Accepted Answer

Greetings! As I don't know this application, specifically, I can say that say that Ultra Copper is excellent for sealing liquid coolant surfaces in truck/auto repairs. Temperature, up to about 800*F and pressures exceeding 15 psi will remain sealed with this product. U.C. remains a pliant sealing silicone "glue", but it won't harden, as epoxy does. If you need a sealer that also hastens, look elsewhere. If this is for a flange or any flat, secured surface, you're good-to-go. NO acetic acid in this product, if that's a plus for you.

Question 4

Can I spread this on outside of exhaust manifold leak like you would caulk something or does it have to go between parts?  F150 '04 V8

Accepted Answer

It is too much pressure and heat to use any caulk or rtv. Even muffler cement doesn't work. You might have a lean fuel mixture to cause the problem in he first place. Exhaust bolts rust solid from heat erosion, use the right amount of points on the socket to get bolts out(6 sided bolt--6 sided socket) Copper metal exhaust gaskets work well. Mr. Gasket brand.

ASIN	B0002UEOPA
Best Sellers Rank	#1,868 in Automotive ( See Top 100 in Automotive ) #5 in Gasket Sealers
Brand	Permatex
Customer Reviews	4.8 4.8 out of 5 stars (3,375)
Date First Available	June 3, 2025
Exterior	Painted
Is Discontinued By Manufacturer	Yes
Item Weight	3 ounces
Item model number	81878
Manufacturer	PERMTX-LOCKT
Manufacturer Part Number	81878
Model	Permatex 81878
National Stock Number	8030-01-598-1435
OEM Part Number	PMT81878
Product Dimensions	8 x 4 x 2 inches
Special Features	Forms a superior bond on oil contaminated metals and maintains outstanding oil resistance

Permatex 81878 Ultra Copper Maximum Temperature RTV Silicone Gasket Maker, 3 oz. Tube

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