What mileage when you had to replace valve seals?
 

I'm toiling over whether to change valve seals or not as I have the cam tower off.

Engine is a very low mileage unit and burns no oil. 62K miles.

What is a rough estimate of their life expectancy in miles?
Are these seals affected by age the same way as o-rings and other rubber seals? They seem to me to be of a longer lasting material.

so how bad is it burning oil on startup and high engine load?

It does not burn oil on startup or under load - yet.
I'm simply trying to find out how long they can be expected to last on a street car.

Where is the option for over 200K?

:) good point. Unfortunately I can't change the poll once it's done!

I voted 100K because that is when my head gasket went.
The seals may have been OK.
If you decide to install new valve stem seals, there are a couple varieties besides rubber that come in the Victor Reinz HG kit.

Judging by the poll mine should last another 100K at least. However, when I took of the exhaust manifold I discovered a blob of black crud on the bottom of one of the exhaust valve guides. Could this be burnt oil?

Judging by the poll mine should last another 100K at least. However, when I took of the exhaust manifold I discovered a blob of black crud on the bottom of one of the exhaust valve guides. Could this be burnt oil?

It could, and most likely is. It would appear that you have a leaker. With such being the case, good time to replace the set. I guess you could just replace the bad one though.

P.S. - I will have what you need when I replace my compressor section with a K27 compressor, tentatively slated for may or june. PM me at that time if still needed.

Make sure you get the reddish colored vitton seals rather than the regular black rubber ones. The vitton stays pliable longer.

The ones I have are grey on the outside and rubber red on the inside. Are those the ones?

I don't know.