[1997ThunderbirdLXV6]

On the subject of Seafoam, I added it to the fuel and I did the intake spray.

The one thing I haven't done is adding it to the oil. My plan was to add some approx. 200 miles before my next oil change.

But looking in through the filler opening, I wonder if there's even a point. It looks pretty clean in there, doesn't it?

 

[97 30th]

Yes it does.

 

[1997ThunderbirdLXV6]

Yes it does.

Well, the seller told me that the car had been meticulously maintained. Maybe it's actually true. (I mean every seller always says that about every car.)

 

[Rocketdog]

They all look pretty clean from that view.

I would be very cautious of putting any substance in your oil. Any at all.

The gunk you are after lives in the components downstream of the throttle body, and inside the combustion chamber, intake and exhaust ports of the head. Not internal to the rotating assembly.

If you use Motorcraft synthetic blend oil, you should have no issues of crud building up, it is very good oil.

Frankly, your best bet is to pull the intake and exhaust manifolds after doing the Seafoam routine. The Seafoam will soften the crud nicely.

Then you can pretty much spoon out the bulk crud, and further clean with a brass brush and Seafoam spray until spotless.

My SOHC had about a Dixie cup
of crap in both the exhaust and Intake ports and manifolds. About 12 Dixie cups half full came out
My DOHC had about half as much. Still, it was enough to actually spoon it out.

 

[1997ThunderbirdLXV6]

If you use Motorcraft synthetic blend oil, you should have no issues of crud building up, it is very good oil.

So how come you had all that crud? Bad maintenance by previous owner?

 

[1997ThunderbirdLXV6]

Frankly, your best bet is to pull the intake and exhaust manifolds...

My only real motivation to do that is that I'd like to clean the injectors. Otherwise, ugh, this looks like a cumbersome job (?), at least from what I've seen on YouTube. I presume that I'd have to replace whatever gaskets there are, too.

 

[Grog6]

Anyone who suggests pulling the manifolds after a seafoaming is not someone I'd take advice from, lol.
I usually put a half can in the oil and the rest in the tank, at oil changes.
It will come out black.
Also, adding a few ounces of trans fluid to the oil after a change swells the rubber seals, and helps with the valve stem seals leaking.
To clean the injectors is not easy, and takes some equipment. I'd look for refurbed ones on ebay.

 

[Rocketdog]

My point was not real clear.
Pulling the manifolds is a job, and best done when upgrading.
I pulled my SOHC intake after looking at it with a scope before and after the Seafoam
I pulled my DOHC manifolds prior to installing the engine.

The Seafoam did not really do much on its own beyond a spectacular smoke show. It did soften the gunk.

Both cases revealed a surprising amount of gunk, and I doubt 1 can of anything would remove it. Maybe if it was repeated many times, it would remove more.

Beyond working well as a parts cleaner, I can't say that it does a lot. I do add it to fuel on occasion and it is my go to upper engine parts cleaner.
Put stuff in your oil at your own peril, I won't condone it.
To truly clean a 20 plus year old intake and or exhaust manifold, there is no substitute for manually cleaning them.
The mechanic in a can BS espoused on here is amateurish at best.
These cars can vote and buy a drink, and there ain't no way a can of stuff will remove 20 years of gunk.
The Seafoam smoke show is cheap entertainment, that's about all.

Good luck!

 

[1997ThunderbirdLXV6]

These cars can vote and buy a drink

Nuff said.