Replaced intake gasket, now what?

[72superBB]

If you have been following me, I have found the problem. I pulled the intake tonight. The back drivers side bolt was not even tight and it had some light brown mucas all over it. There were other bolts that were not really tight as well. I pulled the rest of the bolts out and pulled of the intake. There was rust all over the back drivers side area around the water port. There was coolant sitting on the top of the motor as well.

I am going to change the oil Monday night. I also replaced the thermostat as well. How long should I drive it around before I change the oil again. Should I change the filter both times as well? I hope this is the problem I have been having.

thanks for your input!

Ron