Define "Sludge"

Messages
57
Location
Leesburg, IN
I'm at a friends house in cincinati right now. earlier today one her friends did a coolant flush on her 94,Grand AM (with 91k miles) and while they were doing that I was checking some of the fluids in the car, and while checking her oil I pulled the dipstick out and nearly freaked out. There was a "large" amount of this white foamy-wax like substance (think lard) stuck on her dipstick! I cleaned it off and re checked it and sure enough I got some more out. Is this engine sludge? What ever it is I know it cant be a good thing, the oil checked fine on the level and it looked fairly clear but that foamy stuff was freaking me out! What is it? and how do you take care of it? and how do you prevent it from happening again?
 
Messages
1,902
Location
cali
if its white and foamy then it can be coolant leaking into the system. yucky stuff...i know if it is that then the oil will become watery milk..but u said sludgy? haha then it may be a combo of ne thing...including sludge AND headgasket leak
 
Messages
47,627
Location
Duvall WA - Pacific NW USA
If whitish this is typically a sign of water - either condensate or coolant. Typically this mayonnaise like, thixotropic goo is NOT my definition of sludge. Still - the oil system should be flushed, oil analyzed, etc.... Sludge is a bit of a broad term. In my vernacular is nasty oil breakdown products. Thick clumpy crap, ranging from brown jelly to hard coke.
 
Messages
3,680
Location
Chattanooga, TN
On another side if the engine was not heated up this past winter, short trips, the condensation can accumulate and what you see on the dipstick in nothing more then this condensation. Usually no sign of serious illness and the key will be if, after an oil change, does it re appear this Spring and summer. Should not...
 
Messages
254
Location
Calgary AB
Your unlikely to find "sludge" on the dipstick. It really only develops on hot surfaces and once there doesn't move too much. I did get varnish on the dipstick of a 5.3L Vortec with a winter fromt installed. This truck idled quite a bit this winter and where the dipstick is close to the exhasut manifold some varnish developed, right at the rivet joint (for those familiar) the oil was 5W30 formula shell.
 
Messages
49
Location
MS.
I had some of that white awful stuff in a car I use to drive. I found out I just wasn't driving it enough to get it warm enough to dry it out, so to speak. Changed oil and drove it a lot more at a time, so it heated up the oil, and it stopped doing it. Had it for a long time after that and never had another problem. So I said that to say this, is she driving it more than very short trips??? If not, she needs to drive it longer at a time. Sounds more like that than antifreeze to me. But it's hard to say, unless one knows more about it.
 
Messages
70
Location
Maine
I have some White Lardy stuff on the inside of my Oil Fill Cap, what is that? Its not on the Dipstick though, and the oil looks fine. Sorry to change fromy our question [Roll Eyes]
 
Messages
3,845
1978, condensation moisture at best. Possible coolant ingression at worst. Clean internally with a bottle of Auto-RX then change oil. If you have any evidence of internal coolant leakage get repaired ASAP. A oil analysis can answer the question. Could just be rarely driven or the last time you cleaned the engine with high pressure water you got some in the oil.
 

MolaKule

Staff member
Messages
21,577
Location
Iowegia - USA
Sludge: A deposit primarily composed of oil and combustion products which does not drain from surfaces but can easily be wiped off with a cloth." BTC subcommitte, 1979. Sludge deposits vary widely in terms of consistency, water content, color, solids content, location where found, and operating conditions. Initiated by mostly blowby gasses and moisture. Sludge binders are condensates in a hydrocarbon phase containing a large amount of nitro-nitrate species and an aqueous phase containing formaldehyde. After condensing on the cold parts of the engine, the hydrocarbon phase undergoes complex reactions in the crankcase. These reactions are promoted by higher temperatures when oil is circulated over the pistons. The organic portion of sludge contains carbonyl, sulfur, nitrogen derivatives, polymerized hydrocarbons, and water. Because they produce increased nitrogen oxides, lean burn engines are more prone to sludging than power plants operated under rich or stoichiometric conditions. Foul air venting systems and low temperature operating conditions are known to be severe in terms of sludge formation. Low crankcase capacity and long drain intervals increase the amount of sludge binder. Fuels with low volatility increase the concentration of unburnt hydrocarbons in the crankcase as well.
 
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