Dan,
Replace, or not to, replace antifreeze can be a super long reply.
I'll try to keep it short.
Lots of items come into play on this:
1. Improved Anti-freeze
2. EPA regulations on hazardous material
3. OEM's need engines to last 100,000 miles for emission reasons
4. Expected lifetime of a vehicle.
For my 2000, I use the "long-life" antifreeze. More expensive,
but has a 4yr/50,000 mile life. Recommended for aluminum engines.
While living in Germany, they did NOT flush radiators. The
hazardous material was to difficult to deal with. VW sold
a "one liter additive" that was an additive package to be
put into the car (after draining a quart of fluid out). It
was the anti-corrosion, water pump lube, all that good stuff
additive.
Don Potter made up some neat "anode" water outlets. Zinc bar
in them to prevent alluminum erosion. Pure Water is actually
better at the transfer of heat for racing! Antifreeze/water
mixture will boil at a higher temperature than plan water
but actually transfers less heat. So for a race engine something
like 10% antifreeze is a good idea. Hence having a sacrificial
anode is not a bad idea.
Depending on where you live, and the hazardous collection, it
will vary. NEVER POUR ANTI-FREEZE down a storm drain. Draining
in the driveway, and letting it run down the street is not
recommended. Used to be in Texas, they ask that you FLUSH the
used antifreeze down the toilet, but now the recycle places will
have a drum for it.
Nissan has always used a "long-life" coolant that they did not
recommend replacing! Odd, but those stickers have been on the
cars since the early 1970's.
With all this... what do I do? Every FOUR YEARS a complete
drain, and replace the coolant with the expensive long-life
coolant. Little mileage on the roadsters, but will run about
a 30% antifreeze/70% water mixture. 7 psi radiator cap.
[Older radiator hoses are good for two years, newer seem
good for four years... hence good time to change the
hoses. Oh, for '68-'70 roadsters I'll replace the heater
hoses with the super good Goodyear hose (silicone?) that
cost something like $3 a foot. Usually found from industrial
/truck supply stores... not Autozone, etc].
Cheers,
Tom Walter
Austin, TX.
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