Advice / pointers on replacing valve seal

Ricks70Duster340 said
Why are you only replacing one seal (on #3)? Was it torn or broken? Normally it is best practice to replace all of them at the same time if they are cracking. Once they crack, they often are very brittle and start to fall apart.

So far since I've had the car I haven't had any issues at all. The previous owner told me that from time to time the #3 spark plug will get covered in oil and it'll start running rough. He said the #3 valve seals need to be changed. . .I'm hoping it was an install error or something, the engine has about 4k miles on it and was built about 10yrs ago