Will Sea Foam help remove coolant from engine oil? [SOLVED]

In a 4.3L engine, the intake manifold gasket ruptured letting engine coolant mix with the oil. We have removed the manifold and cleaned what we could.

My plan is after putting the upper back together, I will add synthetic 5W-30 with a new oil filter, get it running to go about 200 miles, then do an oil & filter change. Then go about 1,000 miles before the next oil & filter change. Then drive the normal recommended miles before the next oil & filter change.

My question is how to dry out any remaining coolant? Should Sea Foam be added to the oil at initial 200 miles, the 1,000 mile phase? Or what would Sea Foam’s recommendation be?

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Jim D.
Jim D.
2 years ago

Hi Randall. Thanks for reaching out to us!

Using your imagination here, understand that radiator coolant is water-based and heavier than petroleum motor oil, so will not blend with the engine oil. When you run the engine, any leftover coolant liquid that might be in the crankcase will emulsify/churn with the motor oil, allowing 100% of the coolant to be temporarily suspended in the motor oil liquid. Once you stop running the engine and let things sit for a bit, the coolant will separate from the oil and settle somewhere under the oil.

What I’d do:

  1. Add new oil to the crankcase (can use budget oil) + add half a can of Sea Foam or High Mileage into the new oil.
  2. Run or drive the engine for at least 10 minutes to heat and circulate the oil, then shut off and check your oil level dipstick.
  3. If the oil is clear/normal, there’s no coolant in the crankcase. If milky brown, there’s still some coolant in the crankcase.
  4. If milky, have a plan to dump the oil. The key is to drain the oil immediately after you’ve run the engine so everything is hot and emulsified – that way you know that all of the coolant is suspended throughout the oil phase when the warm oil is drained out.
  5. Also note that water or coolant in oil won’t stay in a crankcase over time because the high temp of the heated oil is always causing water to evaporate while the engine is running.

Hope this helps!