Sludge problem in oil pan

We have a 1998 Grand Prix with a 3100 in it the last person who had it blew the intake gasket; which didn't look like it was installed properly, anyway there is thick sludge (antifreeze and oil) in the oil pan and we have been trying to figure out how to clean it out without removing the pan which would mean pulling the motor. Does anyone have any suggestions?

Run about 5-6 ounces of Seafoam engine additive or any similar additive directly into the crankcase for a short period of time, run the engine and then drain out. Then new oil and a new oil filter.

And welcome to AF.

the last person who had it blew the intake gasket; which didn't look like it was installed properly

Why do you say that? There is really only one way to do it. I would defenatly look into this.

If there is antifreeze in the pan it's probably too late. How long did they run it like that.