[RichH]

It doesnt matter how the oil 'looks' as when it gets hot it 'boils' out the water leaving the salts behind.

In order Id check the following:
1. Pin hole leak in the exhaust manifold ... causing water to be sucked into a combustion chamber after shutdown.
2. Blown head gasket - ditto above + engine pressure leak down test (leaking into the crankcase, especially) .
3. cracked warped cylinder head
4. cracked block -- fluorescing dye placed into cooling fresh water now 'showing up' / fluorescing in crankcase,
5. cracked turbo oil heat exchanger if you have one.

Pressure (Hold) testing each component in situ or removed and disassembled is the only way to go - IMHO
You can narrow down those choices by adding fluorescing dye to the fresh water side and then examining oil, cooling water under 'black light' to make the oil fluoresce or alternate dye to check for CO in the cooling water, or crankcase oil.
Choose the correct fluorescing dye for the specific area of the engine youre inspecting.

 

[RichH]

I didnt see the part about the 'over-heat' incident.

Consider:
The overheating incieent would be my highest index of suspicion .... the stretching of the cylinder head bolting due to the extra heat and the relaxation of the 'clamping pressure' that the head bolting provides - blown or leaking head gasket AND/OR heat stretched head bolts.

This is easy to analyze without a cylinder head 'rip down' - go to an auto supply shop that caters to 'auto racers', get some of the fluorescent dyes that are used to detect carbon monoxide in the cooling water. When/IF CO gets into the cooling water the dye will fluoresce when 'black light' is shone into the water.

Do this first before you re-torque the head, and then re-torqueing with 30wt oil to lubricate the studs and re-torque SEVERAL times in succession so that you get correct torque.

Then repeat with the dye AFTER changing the cooling water and repeat with the fluorescing dye analysis to see if the re-torqueing was successful .... if not, replace the head gasket (which is probably leaking between an oil gallery supply port to the overhead valves and a cooling port within the head gasket ... plus into a cylinder).

 

[RichH]

If it is salt instead of coolant & the exhaust manifold is salt water cooled, the manifold may be leaking salt water into the ports? If you are not losing any coolant the only other source I can think of is salt water in the fuel that is getting past the filter/separator? That may be a stretch, however. It would be interesting to know what you find.

Paul T

PIN-HOLE between the gas side and the water side of the ex. manifold .... quite common in engines that have been in service for awhile, and especially in engines that are 'drained' of cooling water for long term layup / winter layup.