The oil-soaked handwriting is on the wall ... TMZ has learned "Jersey Shore" is about to lose 4 familiar, overly-tanned faces in Season 3 ... to make room for 4 fresh overly-tanned faces.

Our spies tell us ...  the footage that was already shot of Sammi, Ronnie, Vinny and Angelina has  "underwhelmed" MTV honchos. As for replacing them for Season 3, one source said, "They should be very worried."

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As for The Situation, Snooki, Pauly D and Jwoww ... they're sold for next season.

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