Celica Forums General Discussion General Head gasket or warped head?

Hi everyone, I own a 100k miles 2003 7th gen Celica VVTL-i with the 2zz in manual, it's my first car that I'm wrenching on personally. I do have some mechanical knowledge as I was a former Navy technician, but I am kind of stumped as how to diagnose my engine issues...I'll describe the symptoms, and some possible leads to what happened before.

Before I proceed, I have to admit I didn't do the appropriate maintenance needed when having bought a new vehicle.... but I have definitely been humbled after the issues I've faced...

Current Symptoms:
- White smoke blowing out of exhaust
- Oil in coolant (see attached pic at bottom)
- No coolant in oil
- No visible leaks (at least to my knowledge)
- No cabin heating
- Temperature gauge shot up to high, and back to mid (air in coolant lines)
- Previous owner used water, not toyota red long life coolant

The journey from working engine to problem:
- Bought the celica, everything seems fine.
- Drove ~400 miles from Leeds to Oxford and back, no issues (generally didn't go above 6k rpm to engage lift)
- changed oil, previous owner was NOT diligent in changing oil, very dirty.
- Went for a spirited drive (went up to 7k RPM), power steering failed.
- Initially thinking it was just a pump failure, I carried on but lost spark & all electricity. Engine temps spiked, and I immediately pulled over.
- Got it towed to a shop, they rang back and realised both the Serpentine Belt & tensioner itself broke on me.
- Got celica back, everything seems fine. Battery went flat from sitting too long so garage gave me a jump.
- Went for another spirited drive (redlined), no issues.
- I did turn off the A/C when at >8k rpm.
- The next drive, I realised the temperature gauge spikes to max and back to mid, indicating air stuck in the coolant system.
- Cabin Heating stopped working at the same time.
- Noticed more white smoke than normal coming out my exhaust. (it was a cold day, so I thought it was normal)
- Brought the car back home, and let it sit for a while to check for leaks.
- After letting engine cool down, no leaks found, cloudy particles found in coolant, no coolant in oil.
- lots of white smoke coming out from exhaust upon startup.
- Oil & coolant drained upon discovery, no coolant in oil, oil found in coolant.
- Discovered previous owner never used toyota red long-life coolant, but seems like he just used regular water.

I always let the engine warm up before heading off, and it's not my daily driver, so it usually only sees usage once a week or so.

Potential diagnosis:
- "coolant" evaporated when engine overheated upon serpentine belt snapping, left air lock inside and when I redlined it, causing uneven heat dissipation, breaking the head gasket or warping the head
- ice built up due to the cold temperatures and improper coolant, maybe cracked head or cracked head gasket


I intend to take out the engine & do an inspection myself, probably send the head to a shop to get it checked. The thing is, I am aware that the head gaskets on these cars simply do not break even with gross overheating, so I'm wondering if perhaps I'm overthinking this and it's a small fix.

Hoping one of you wise people of the forums has a contrary opinion or spot something I may have not realised!

I should add that I found out there was no water in the oil because the dipstick and engine cap is clean!

I drained the oil and also found no water inside.