Oil in coolant - 2 litre

[David Masters <david@domain.elided>]

Fellow Alfisti,

I had the sickening experience of finding emulsified oil in my
overflow tank on the mighty 2l Twin Spark over the weekend.  Of
course I thought this would be terminal, and psychologically
prepared myself for a head gasket replacement.
Before commencing I borrowed a dye kit, and got a negative
reading on the contents of the cooling system, and so then
proceeded to do a thougher clean of the cooling system, using a
chemical flush, including removal of the overflow tank, and giving
it a good wash out with kitty litter and kero.
Refilling it with new Coolant, there is now no evidence of there
ever being a problem.
What are the leading causes of oil getting into the coolant, and
are any of them repairable?  There is no sign of any oil
contamination in the sump.
Without understanding why I got a "negative" on the dye test, I
can't help thinking it is a head gasket that would let oil into
the coolant, but it might only happen under high load conditions.

Any comments?

Cheers,
david
-- 
David Masters, 1989 ALFA75 Twin Spark, 100000 miles.
Full Synthetic Engine Oil used for the life of the car.
Newcastle, AUSTRALIA.
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