[Lynn]

Was asked by a member "How do you know it doesn't leak at the hairline crack?"

I put some oil in the valve cover at 11 this morning. See first pic below.

I took the second pic just a few minutes ago, more than 5 hours later.

Second pic was taken from below with the oil still in the valve cover. As you can see, there is NO seepage.

These came off a running engine and it didn't leak then, even before the epoxy repair was made on the inside.

Let me know if you have any other questions. I would not hesitate to run these on an engine. I already have the correct valve covers on my car, and just do not need these.