I've been using Propylene Glycol for years in my many vehicles and have never noticed a problem with corrosion.

I've had it in a 300D for about 6 years and it just works. Had the thermostat housing off recently and it looks fine.

I've had it in an '81 VW diesel since about '91.

Ingest enough Ethylene Glycol and say goodbye to your Kidneys.

I would replace the heater core and then put the Prop. gly. in. Then the heater core will probably never fail again.

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Diesel-guy