how much oil? does it look like chocolate milk in the coolant expansion tank? or are their some oil droplets and oil sticking to the tank sides?
Have you ever used Redline brand WaterWetter?

At 145K miles SOME say it would be normal to have some small oil deposites.

Do you know you can perform oil analysis on your engine oil and transmission oil to help guide you to whether things are normal or in need of repair.

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