Bubbly oil on the dipstick is sometimes caused by "frothing". This occurs if TOO MUCH oil is poured into the engine..ie..during an oil change, which you just did.

Check your oil level on a flat surface after the car has been at rest overnight.

I wouldn't push the blown-head-gasket-panic-button just yet.

My 2 cents.

__________________
'91 300-SEL