Valve cover gasket shelf life

Do they have a shelf life?

I have a Yamaha valve cover gasket still in the factory bag and has been stored in closed box for an unknown number of years. It's still pliable and has a healthy amount of that white powder on it but has some memory of it's stored condition which was all rolled up. I have it laying flat now to see if it will relax. Maybe a drink would help.

 

That's a good question. The lifespan of rubber is surprisingly short, as many of us have discovered, and also why even tires are supposed to be replaced in 5-7 years regardless of mileage. That said, there are a lot of variables that lead to rubber degradation, such as exposure to both air and sunlight.

With something like a gasket, you can pull on it in 4" sections at a time. When do that, do you see any tiny cracks? Look CLOSELY. If not, I'd go ahead and use it. It's only a valve cover gasket and it's not too bad if you develop a leak after a couple of months and have to replace it.

But what my experiences have told me is that I stay away from OEM stuff, and prefer to buy the aftermarket if I know that the date of manufacture is more recent. I have a great example of when I bought OEM muffler gaskets on Ebay that I thought were a deal (I know, they aren't rubber, but it's relevant!). Those gaskets are expensive. Well, they tended to crumble when I clamped down on them. I had to buy a replacement from XJForever for a few extra bucks, but they were much better made. Lesson learned.

BTW, when I take off some rubber piece off my bike for the first time, I put it in a tin can and spray it with silicon lubricant and let it sit for a while. I heard once that it ca absorb it and helps preserve rubber and keep it flexible. Maybe some others have input if this works.

 

I'm on my 2nd one and it's over 5 years old.

I have a ritual I follow that keeps it young.
The New Gasket gets a Armoral dip.

I use a trace of Elmers Glue for pre-mounting.
Before mounting BOTH Gasket and Head Mating Surfaces get "Painted" with Marvel Mystery Oil.

Lets the Gasket Spread-out when being tightened.
Keeps the Gasket from drying-out.
Simplifies next removal.