Oil changes and Coolant changes AD #833

["C.M. Smith" <cmsmith@domain.elided>]

I think the practical limit of synthetic oil longevity in the engine is
probably contamination, not oil breakdown. The 164 owner's manual suggests
10,000 mile change intervals...or once per year.  The "or" is very
important. The two sources of contamination are dirt from the combustion
process ( and a bit sucked through even the best filter, or a dirty filter
that's why changing an air filter that looks 'pretty clean' at the
recommended interval is also a good idea) and fuel/ water condensing during
short trip or cold weather driving. Even sitting without turning a wheel
will eventually contaminate engine oil with water condensing out of the air
inside the engine at a rate that fluctuates with humidity and temperature
variation.

I time the annual oil change on my 164 to coincide with the coldest winter
weather on the theory that the water contamination will be at its peak and
the engine benefits most from fresh clean oil when running cold and
frequently used for short trips. The ski trips I take more frequently in
the period from Feb to May then keep the water contamination to a minimum
because the oil gets nice and hot and any water is vaporized and consumed
through the crankcase ventilation system.

On the coolant thread:   I strongly recommend against using less than 50/50
glycol/water in the cooling system for several reasons. First, glycol/water
has a much higher boiling point, as well as the well known lower and less
damaging freezing temperature. Second, the moose juice that keeps the iron
from eating the aluminum is found only in the glycol (although boosters are
available for adding regularly). Third, the glycol also has a water pump
lubricant in it. Even with these modern long life coolants I ask for a
coolant flush and replacement (for the car, my system operates best with a
daily flush of red wine) at least every two years to minimize corrosion
risks. Granted, Alfa engines are mostly aluminum and not much iron (steel)
but it's cheap peace of mind and keeps your water pump happier.
Michael Smith
Calgary, Alberta
Canada
91 Alfa 164L, White, original owner 

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