Fusion Ultra-Strength Oil Stop-Leak® works by re-impregnating the seals with silicone, the seals absorb the silicone they've lost overthe years and expand backto original size and stop the leak. Our Oil Stop-Leak workson all engine seals, rear-main and oil pans...Fusion Oil Stop-Leak is alsocompatible with all engine oils.oil filters & oil coolers too.