In my Peugeot 406, manufacture year 2001, engine 1.8, very recently I had overheating issue due to thermostat valve block. I have replace thermostat valve and now I can see engine oil mix with radiator coolant. When I check radiator I can see milky oil in radiator.

I try to fix this without replacing cylinder-head-gasket using "steel seal head gasket sealer" but I realize it only seal radiator to engine leaks. (radiator coolant leaks to engine.) but I have engine oil comes to radiator.

is there any sealant to stop engine oil leak to radiator or do I need to replace cylinder-head-gasket?

plz help me. Thanks.

  • You tried to use a sealer and it didn't work? Oil leaks to the coolant system aren't fundamentally different from coolant leaks to the engine if a blown head gasket is the problem. The sealer could fix them both unless the gasket is really done. Feb 15, 2016 at 8:30

2 Answers 2


is there any sealant to stop engine oil leak to radiator


or do I need to replace cylinder-head-gasket?

Yes. But also you need to have the head and the block checked for warping. They head might need to be re-surfaced.


Forget all the "quick leak fix sealants" because they tend to make more harm than good in long run. If you had recently overheating issues, cylinder head is probably warped and seal is shot. And needs to be replaced.

Another common cause which can leak oil into the coolant is the engine oil cooler, which is located directly before oil filter.

  • To be fair, while the sealants are never a permanent solution, they sometimes help to get some extra miles from a car that would be scrapped otherwise. So it does have it's uses. Feb 15, 2016 at 16:24
  • Also they can make blockages, which can lead to another overheating. Feb 15, 2016 at 19:53
  • Which isn't that horrible if you were about to trash the engine anyways. Feb 17, 2016 at 8:15

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