i own a 2000 buick century custom. a couple months ago i had oil in my coolant/antifreeze so i had emptied it out cleaned and had put it back. well since that day my car wont start and now pops the IGN 0: cluster, pcm,& bcm 10a fuse. i have replaced the ignition switch, fixed the ignition column, flipped the starter, checked the fuse box yet it still keeps popping.i will be tracing wires to look for a short or grounded wires. any suggestions on what to do?

You have a cracked cylinder head or block

hopefully it is just a headgasket.

I don't think the oil in the coolant has anything to do with the fuse. I suspect the people that did the work damaged a wire or connection while changing the coolant. Also the oil may actually be transmission fluid since the transmission fluid is cooled in the radiator....a crack in the transmission cooler would leak into the coolant. I would take it to a different shop and have it looked at again and they may also find the blown fuse problem

I'm banking on head gasket or a cracked head and I bet u that dinner night

Oil in the coolant , and especially if it has backflowed into the reservoir, is always transmission oil cooler lines, when the lines run through a radiator. The oil in the coolant Inside of the block is not your biggest problem that can easily be drained and flush. Your biggest problem is when oil cooler lines rupture inside of a Radiator nine times out of 10 you're going to now have coolant in your transmission. That's the problem because dropping the transmission in Flushing it out its way way more time-consuming and extremely expensive than flushing out a radiator.

What ever happened to your pcm/fuse popping what was causing it?. I am having the same problem. Thanks