I bought this car around 1 year and 3 months ago, it hasn't been driven since as I am only 15. I believe the yellow goopy stuff under the oil filler cap is condensation, or is it a blown head gasket? A lot of water does come out of the exhaust when the car is running. As for the coolant, there is a slight leak in the radiator (shown on one of the photos) which could explain the loss of coolant. I believe losing coolant is also a sign of a blown head gasket but I doubt it is in this case as the radiator has a leak. As for the engine, it is a 1.2l 16v petrol, heated up to temp most days, not been driven on a road in a year or so. The oil was changed a few months ago, so I believe it looks like that because its newer oil, it doesn't smell like coolant and there doesn't appear to be any coolant mixed in so I assume its fine.