Ok i get it now, that reading was from the oil.
I thought it was from the windings.
I check at work what it exactly means. I take the occasional oil samples but these get sent off to the lab and rarely get to see the results. Usually whe a TX passes, it's fine, no further enquiries needed.
The 1200 Amps loading is well within it's 1000 kVA capacity, no problem there.
I would suggest to do some insulation tests on the HV winding especially, with cables disconnected.
It doesn't sound good with considerable fibre content in the oil. Something is defenitely deteriorating there, or the tank was dirty prior to assembly of the core.
Any signs of carbon traces in the oil ?
