Chevy & GMC Vans

I have seen some cans of a substance that is supposed to be added to the crankcase right before an oil change and run for a hundred miles or so to clean out the inside of the engine.

What do you think of these things? Is it possible they could do some damage?

Many of the members here will tell you to use seafoam(sp) to clean out a engine.Here is my two cents on high mileage engines in terms of that.I think there is build up in a high mileage engine that is not doing any harm as it is now that is taking up some clearances of worn parts and seals.Freeing that up makes that build up travel thru the engine during the cleaning add the posibility of damage and afterwards increases those clearances and the possibilty of leaks.I think the only repair of a high mileage engine in terms of renewing it,is the rebuilding of it's self.Surely do your oil and filter changes,tune-up's,greese,but if it ant broke.........

Gary hit it right on the head. If there is any sludge build up in your engine you really want it to stay right where it is. If you break it loose it will cause problems. If you do regular oil changes you wont have any sludge.

Like ever vehicle I have owned, when I bought my 04 Sierra I took it to get the oil changed.
It had less than 1000k on it.
The guys at Minit-Lube recommended a crank case flush, as I was changing the oil from organic to synthetic. I had never heard of a crank case flush but Minit-Lube is warranty approved and getting rid of the irregular shaped organic oil molicules made sense to me.
Immediatly after having this done it felt like they had pulled out the 6ltr. and replaced it with a 2 cylinder Yanmar. It just seemed to have lost a lot of it's hootspa. I still own that truck and I have not had a single thing go wrong with it but I would never flush another engine again.
I have never been a big fan of "snake oils" and this experience confirmed my position. Regular oil and filtre changes along with proper PM is the only way to go.

I don't want to rock the boat, but... i used seafoam in my '98 3.8 Intrigue to bust up the sludge with 240K on it. It runs like a new motor now. It never used oil before or since, but it is gettin 2-4 MPG better than it was. it gets about 29-32 MPG now, despite the mileage and 3 trans replacements. I vote for Seafoam in the crankcase and the fuel tank, but the rest of that stuff is of no value, except to line the pockets of the manufacturers...

Rocking the boat is just fine as long as you are respectful. Other opinions are how we learn. I agree, Seafoam is a good idea when used through the intake manifold and in the gas tank. It cleans out a lot of crud. I've used it and it has never hurt a thing.

Thanks Smiles. I really don't like using that "fix in a can", but I swear by Seafoam if you use it according to the directions on the can. I really like to smoke out the neighborhood when I do the intake cleaning too! Something about the pyro in me, I guess.

cool isn't it. Well kinda scared me the first time. I've poured seafoam down the intake, and metered it in throught the pcv hose. That first restart kinda looks like ole faithful doesn't it? I think the words holy s**t passed by my lips.
I did seafoam in the crankcase one time, don't know that it did much, but maybe it wasn't that bad to start with. I used it to clean parts when I did my trans rebuild. I have to agree that it's good stuff. but... do follow the directions on the can.