They do.
The only 2V modular stem seals that were a problem were the '91-'95 models. Ford changed the seals when the heads were slightly redesigned for the revised NPI port in '96 with the F5AE castings, and the stem seal issue went away.
JL

 

But it IS worth it to replace the entire engine - AGAIN AND AGAIN AND AGAIN?

I think you might need a new mechanic.

 

I think you're reading into it all wrong. The reason it might not be worth the cost and effort to fix the oil consumption is because you could simply add what it has consumed every 500,1000 or whenever miles. The $2-$3/quart is a rather cheap bandaid to the still bleeding wound and no down time. I think his son replaced the engine over and over again because he didn't know about the common consumption problem and/or was taking a gamble to see if he could get one that didn't consume mass oil. I believe his mechanic is stating that it isn't worth it to fix the valve guides and to just live with the consumption.

As for the other gentlemen about it being news to him concerning oil consumption.... I was wondering the same thing and I've come to the conclusion that most owners do NOT know how much oil came out because it is brought to a shop to be done or the left over oil is simply dumped into one larger container for recycling in bulk earlier. Also, those drain pan/storage container combo devices have become very popular. You still can't see how much has drained into the container when it is dumped into a larger mass collection container still.

I do my own oil changes and about 5 years ago I got into the habit of exact measurements coming out of the motor.

When you take it to a shop or dealer, it gets driven over a pit over a mass collection container, or lifted in the air and still oil is collected over a mass collection container. There is no measurement, just speed and efficiency. The oil light won't even kick on till its about 4 quart short and coming down a freeway off ramp to a stop. So I'd have to say a majority of owners probably don't know and wont ever know.

 

My V10 doesn't use a drop of oil between oil changes. As checked on the dipstick before I start it in the morning. None of my Ford modulars has ever used a drop of oil. Castrol GTX 5W30.

 

I'll try a case of that to see how it goes. I recently bought a case of the pennzoil platinum synthetic and rather not use it in this truck at the moment.