Sounds like a head gasket. Get thee to a mechanic ASAP! You can live with oil in the water for a bit, but if you get water in the oil, it's all over (don't ask me how I know)!

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"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles