according to the bentley manual, the tip uses hypoid oil for the differential. this oil has a peculiar odor, but is thicker than engine oil. But it looks like engine oil. the tip also uses atf oil. the atf oil that I've seen is red, but I've never had a auto or tip gearbox before. good luck
Is it possible that the tiptronic's oil cooler could be leaking?
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-99' Zenith Blue 5-spd...didn't agree with a center divider on the freeway
-01' S Orient Red Metallic 6-spd...money pit...sold to buy a house