I did the following diagnosis.
Water was low in coolant, topped about 200ml.
Drove 40 miles to the airport and left car for a week.
Engine on - check coolant, topped another 400ml max and started journey home.
After 10 miles lights on again.
Pulled over and checked the following:
Coolant low in header tank - opened and water returned.
Oil level over the max mark (I never overfill)
No water leaks under car
Mayonnaise on oil filler cap.
After 2nd top up car sounded rough so stopped it carried out above checks and got it towed home.
I will call MRC tomorrow, but would they have done the oil and water checks to see if there was cross contamination?
Edited by Vik, 25 July 2021 - 03:49 PM.