My FIAT 126 engine bay was immaculate. I spent more time keeping it clean than the rest of the car. This photo isn't of mine but the same configuration and a similar standard.
Then one evening I was heading out of town when I noticed something on the rear screen. I stopped, and when I went to look I discovered the oil filler car, which was similar to a radiator cap, had failed and the top had disappeared.
What I saw on the rear screen was fine engine oil. I could have cried.
It took about 3 months to get it back to the state it had been in but I was never happy. It had been sullied!
Mate, you must have been gutted. And probably quite angry!
My Uncle had a Fiat 126 for years. I had a drive in it once, being a fan of the weird and wonderful, and really enjoyed it. Had the choke lever between the front seat IIRC. Brilliant stuff. Mind, being a big bloke, I found it to be a very narrow car. Handled surprisingly well from memory and had direct steering.
They call them the 'Polish Porsche', on account of being rear engined and made in Poland. Also because in the early post communism years, they were the one of the few cars the Polish could afford.