O rings

[Renegade]

Service manual says to replace a couple of O rings while doing valve inspection. How important is this? If they look good, I tend to leave 'em be.

[bigbird]

Service manual prescribes the best way to do a job. In a perfect world you'd replace your O-ring on your oil drain plug at every oil change and torque that plug to factory specs. Do you?

I doubt it. That allows the dealer to charge for everything listed in the service manual. Do you have proof that's a new O-ring or gasket they billed you for? Did you see the tech use that torque wrench?

If the O-ring looks good then re-use it.

There's only one scenario where you need new parts. If you are loosening bolts that require stretching to torque properly, you need new bolts on reassembly. Examples would be the bolts that hold the brake calipers onto the front forks of my Silverwing, or head bolts that attach the cylinder head to the crankcase.