I've heard of heads warping if the engine overheats.
If so, you may also need to shave the head.

Robb S via CarKB.com wrote:
> sounds like a head gasket, or possibly a crack somewhere. If your not
> burning oil, you may be able to get away with replacing the head gasket, and
> having the valves done.
> Pull the head, and have it tested for cracks before rebuilding it and putting
> it back on.
> this MIGHT get you by
>
>
> Josh wrote:
>
>>Here's the latest:
>>
>>I decided to change the oil myself on Sunday morning. When I removed
>>the oil cap, there was a funky slime on the bottom of the cap ( coolant
>>+ oil, perhaps? ). I noticed that I had lost some more coolant, so I
>>filled up the container again. After the oil change, I drove it pretty
>>hard for a couple of hours to see if I could get the oil pressure to
>>drop, and it didn't. It hasn't since, actually.
>>
>>So, this morning, I open the hood, and I've lost quite a bit of
>>coolant. I removed the oil cap, and the funky slime is back. It's
>>looking like Brian might be on to something here. Based on this, what
>>do you all think my options are? ( And yes, I am still in denial about
>>needing to pony up the cash to replace the engine! )
>>
>>Thanks for your thoughts,
>>Josh
>
>
>