White sludge in oil

You didn't mention what engine you have or how many miles on it, if the vehicle was overheated so. It could be a number of things, but in all likelihood it is a blown gasket.(Head, intake, ect)you will have to do the following testing in order to pinpoint the problem. Coolant system pressure test, cylinder compression leak down test, if these two are fine then most likely so is the head gasket. You will have to repeat the test with the oil pan removed to view the inside of the block from below to rule out the block.

I have the inline 6 cylinder 4.0 liter engine. I have 210,100 miles on it. The engine runs appears to run fine and does not over heat, but it gives off a tiny bit of sweet smelling smoke. From what I can tell, it isn't leaking any fluid. Hope that clarifies my original post.

Head gaskets can leak internally, into the combustion chambers, oil return galleries, ect. Sweet smelling smoke is a indication of anti-freeze, Either in the oil pan or in the cylinders (exhaust). A coolant pressure tester fail would pinpoint an internal leak. ( You may also try removing and inspecting the spark plugs to locate a problem cylinder.) Etheline glycol (green or yellow) antifreeze in your crankcase will contaminate your oil, and remove the babbitt from your main and rod bearings, resulting in failure.