I just checked the fluids of my Twingo RS and made de discovery that there is oil in the coolant. So naturally i thought headgasket. But there is no coolant in the oil, no smoke out of the exhaust, no power loss, no fluid loss (at least not that i can see because the fluid level has been the same for a while). So is it possible to be something else than the headgasket? I don't think i have an oil cooler but sometimes theres oil running trough the thermostat housing?

  • The fluid will only move from a high pressure to a low pressure, so if the leak is on the head gasket between a high pressure oil way and an coolant path, then there will be no coolant in the oil, just oil in the coolant. Are you saying that none of the fluids have dropped? How much oil is in the coolant?
    – HandyHowie
    May 25, 2020 at 7:20
  • Is the gearbox fully manual?
    – HandyHowie
    May 25, 2020 at 7:21
  • Gearbox is fully manual, I dont think the oil has dropped significantly, it is still at the half way mark and i didnt refill it since i guess 4 months. There is a small layer on top of the coolant (clear coolant below) so it isn't mixing to mayo.
    – Jeffrey
    May 25, 2020 at 7:56
  • If it has an oil cooler, it may be defective.
    – Moab
    May 25, 2020 at 11:56
  • If no oil cooler, then doesn’t this indicate a crack in block or head somewhere? Has vehicle ever been driven in hot weather while extremely low on coolant? Has vehicle ever been parked in super cold weather without proper antifreeze mix?
    – zipzit
    May 25, 2020 at 14:12

1 Answer 1


The most common cause of oil in the coolant is a problem with the head gasket which allows higher-pressure oil to flow from an oil passage into the coolant. This may be due to the gasket itself or a warped cylinder head.

Less common, but also possible, are a cracked cylinder head or a cracked engine block.

Another possible cause, which you have ruled out with your manual transmission, is a leak in the transmission oil cooler which is usually inside the radiator. Of course this is not engine oil but transmission fluid but it can be difficult to tell the difference when mixed into the coolant.

I'd say your next step is to remove the cylinder head and inspect the head gasket for cracks or splits in the areas between oil and coolant passages.

Some vehicles also have an oil-to-water heat exchanger, often near the oil filter, and this may also be the cause if your vehicle has one.

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