You can pretty easily determine the life of the engine by doing a compression test. Usually a good measure of whether a rebuild would be worth it or not - but agreed with the post above. Which seals are leaking? Obviously some are much easier to change out than others.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth