Coolant issue? Internal leak?
 

Had the car in the shop not too long ago for IMS/RMS and a few other things. Not sure if that is related or not.

Over spring break I got a P0300 and P0304 code (misfire on cyc 4). Found a few drops of oil under the car while changing the brakes. CEL turned off next time I started the car. I was planning on asking shop to scan at the next oil change. Again, not sure if it's related.

Late last week got a red low coolant warning in the morning. Topped up with a little under 1/2 gal of distilled water. Yesterday I was checking the level after work and think I didn't get the cap on tight. Drove about 35 miles at 80+ on the toll road - no lights or warnings. Just as I pulled into the driveway the red coolant warning came on again and the car barfed on the driveway. Cap was loose as I said.

Let it cool down and topped up with distilled water and drove about 5 miles and got a red low oil pressure warning just as I pulled in the parking lot. Had the boys bring me some oil and distilled water. After sitting about 3 hours, the oil level was fine but the coolant was low again. Topped up again and had my son follow me home. He says white smoke appeared when I started the car. Got a CEL and a yellow "drive to workshop" warning on the drive home.

Haven't seen any water under the car (except when it puked on the driveway). Makes me wonder if I have an internal leak (especially with the white puff of smoke).

Shop says I need a pressure test on the cooling system. Hoping it's not an oil to coolant leak. Thoughts / suggestions?

Yes a cooling system pressure test is needed. I would also do a compression or better yet a blow down test. I recommend you park the car.

Hopefully not Intermix ? Search

Some white smoke at startup can be normal.

Once the system dumps, it can be hard to get all the air out. A loose cap allows the coolant to boil at a lower temp.

Take a look at the oil and see if it is the right color. Dark not brown. Check the end of dip stick and under the coolant tank cap for sludge. The oil coolers/o-rings can sometimes fail. Also, check under the trunk carpet and see if it is wet.

Search through Pelican's tech articles, lots of good free info; Porsche Boxster 986/987 (1997-2004) Technical Articles | Pelican Parts

Well so far I know I have an internal leak of the coolant system, definitely getting water in the combustion chamber. Oil "looks" ok but coolant may be leaking slow enough the oil is burning it off. Misfire on cyl 4 was last CEL so compression test next.

Well that is definitely not good news. Please keep us in the loop, as you have time.

It was a cracked head. No intermix, just burning coolant in the cylinder. Bought a used head and had it installed. Had them fix a few nits and leaks while they were in there. Just over a 100 miles on it now. Going to change oil at 1000.

Glad to hear you are back on the road.