The Difference Between Carbon and Sludge

[JCCADILLACMOBILE]

I too have been wondering if "Sludge" can be just "Left In" an Engine, not really harming anything.. and if it is the same deal with "Carbon." My Engine MAY have a Carbon Build-up, and i wonder if the Carbon is in the same place the Sludge is (one or the other, my car runs MUCH better on Higher-Octane Gas.. This is independent of the Jaguar liking 20W-50, though i seem to have taken the route many Jaguar owners take, and went 10W-40... 30% Synthethic to help Flow at Start-Up, even if i DID go 20W-50 when it gets Hot and made this oil a Short "Cleaner" OCI with SeaFoam and MMO, will either of those help Carbon go away, or does it just stay, or does it get "Blown Out" by Driving, usually hard?)

It almost seems as if NO SeaFoam or amount of MMO, B-12, whatever is necessary, as if my Engine has Good Oil pressure (and it does) at the Grade it is at (goes to 35-40PSI Hot idle, 60Psi driving when warmed up,) The Sludge can Stay, No Harm Done, particularly in this engine that likes Heavy Oil.. and this relates to Carbon HOW?

Thanks

 

[addyguy]

Not really - carbon builds-up on the tops of pistons and on valves, from poorly burned fuel.

Sludge is from dirty, over-extenede oil, and is slime that sits in areas of lower oil flow - heads, bottom of the oil pan, and when it gets bad enough, it clogs oil passages.

To get rid of carbon, you want to either run the engine hard enough to burn it off, or use a cleaner like Seafoam, alcohol or even water through a vacumn line to clean it out.

For small amounts of sludge, you don't really need to worry about it - use a decent oil, change it regularly, and it will basically clean itself out. MMO or Seafoam in the oil can speed the process a bit.

 

[IndyIan]

Carbon build up is a by-product of combustion, found in the combustion chamber, exhaust system.
Its bad as it increases compression by taking up space when the piston is at top dead centre, and like charcoal, it can burn slowly leaving a hotspot to preignite the air/fuel mixture causing ping.
What oil you are running has nothing to do with carbon build up or pinging or how rough or smooth the engine in running.

If I were you, I wouldn't worry about sludge or carbon(just run high octane gas) until you are sure the car is going to be a runner for a while. Driving it hard may help remove some carbon from the engine but don't over do it. IF you decide driving an old Jag is for you then work on cleaning up the carbon and sludge. Probably just running HDEO will clean up the sludge gradually to a point where its not going to be an issue.