I think a more important question is 'why' are you getting a sludge
buildup in the first place?  That is 'not' a normal thing to happen and
is usually related to a bad PCV or CCV system.  (crankcase vent)

A buildup of sludge is 'best' removed physically by dropping the pan and
cleaning it out.  Dissolving it will block the oil filter almost
instantly which causes the bypass to open so the sludge just pours back
into the pan or gets pumped around.  This is not good for the engine and
could take a dozen or more filter changes to get the oil clean.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08.  Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

baja...@yahoo.com wrote:

===
Seafoam originally designed for outboard marine engines, primarily for
valves, head.
Try auto-rx.com for engine sludge, but surely removing and cleaning
the pan is best.

How often are you changing your oil?   You may find that you need to
accelerate the change interval.

Another question, what car and engine is involved? There have been some
engines of certain years that have had unique problems which result in
sludging. F.eks, GMs with leaky gaskets or decomposing plastic plenums,
certain Hondas and Toyotas, etc.

As others have said, dropping the pan is best. But I have done other
things....

About 6-8 years ago, my father had a 200,000+ mile farm truck (92 Dodge
Dakota, 5.2 Magnum/automatic) that would lose oil pressure at random. We
dropped the pan and found about 2" of gritty, hardened, broken down
sludgy junk in the pan and the entire inside of the engine coated with
more. Yet the thing ran fine and didn't even burn oil. Figuring that we
couldn't lose, we cleaned the pan, put in a new oil pump (the rotors on
the old one were ground down amazingly), re-installed the pan, and then
attacked the rest of the crap by running many gallons of Kerosene down
each oil fill pipe (one on each valve cover) to rinse down the rest of
the engine. 5 gallons down one valvecover, catch it out the bottom of
the pan, filter it through shop rags, and then pour it down the other
valve cover. We repeated the process about 5 times until no more junk
was coming out the pan.

Then to re-coat everything with oil, we filled it with an absurd amount
(about 8 quarts down each valve cover) of the cheapest non-detergent oil
we could find- then drained that (never starting the engine) and kept in
a drum to use as chainsaw bar oil. Re-filled it with a better grade of
oil than he'd been using, and fired it up. Changed the oil filter about
3 times during the first 2 hours of operation, changed the oil again,
and tried to forget what the insides had looked like. We expected to get
maybe another few thousand miles and a year or two out of it... but
being a typically indestructible Mopar 318 it had other ideas and is
*still* running to this day and bumping up against 300,000 miles. I
think Dad still has a lifetime supply of non-detergent chainsaw bar
oil... :-)

On Feb 25, 8:02 pm, baja...@yahoo.com wrote:

Why do you want to remove the sludge?  It will remain benignly in
place unless someone thins it out with a solvent.  Seafoam is only the
latest of several commerccial and home "cures" for engine sludge.
Unless you want to remove all of the sludge by disasssembly and
clenaing my recommendation would be to leave it alone.

By chemically loosening up all that solidified gunk you run an
excellent chance of plugging an oil hole somewhere.  One of those
cleaners will create the impression of a job well done with lots of
black goo and chunks flowing out.  Remaining unseen but of concern is
all the stuff that was loosened but not evacuated.