It sounds like you have a headgasket problem. Do you have any milkshake like substance on your dipstick? If you do, then that would be water/coolant, in your oil. I would definetly get it looked at ASAP. I am not familar with your eng., but I'll bet it has an aluminum head, and these will warp if she overheats. Hopefully you have spotted this early enough.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section