A related question from the
Fel-Pro support site:
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Q: Is the Fel-Pro P/N 226 RTV compatible with synthetic oil?
A: Our RTV is compatible with synthetic oils. Just always allow it to cure fully for best results. RTV requires 24 hours to fully cure.
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As for spilled oil, I just get as much as I can off with a rag so it won't splatter or migrate into places it shouldn't be like electrical connections. Dirt on the engine will probably absorb whatever's left.