Have a 95 buick centrey 3100 motor that has been driven for a week or so with a lot of anitfreez in the oil.How bad is this engine hurt
This is a common problem with the GM V6. The intake gasket or head gaskets are the culprit. The damage will depend on how many miles your drove. If you really like the car expect to pay $600 to $800 to fix the gaskets. If you do not want to put a lot of $ into it or think you drove it hard you can try some of the sealers, like Steel Seal.
After being driven for a week with coolant in the oil, the mix likely has already stripped the finish off the crankshaft journals and bearings (or very close to it) soooooo, there may well be a rebuild in the offing here.
You MAY be too late for just a intake manifold gasket job.
Have a pro look at it and do a coolant pressure test, IF you do or don’t see coolant leaking to the outside of the engine.
The bill may be substantially higher than suggested by Steve.