Dear Tom and Ray:

You wrote recently that different-colored coolants (regular and long life) can be mixed without danger. Your info might be accurate regarding GM and Toyota coolant, but as a Volkswagen Service Manager, I can tell you that it's not true with Volkswagen bright-pink "life-time coolant." The pink G-12 coolant, in use since 1996, is chemically different from the old blue or green G-11 VW coolants. When these two mix, there's a chemical reaction that causes the coolant to "gel" and turn brown in color. The coolant will get so thick that it can't pass through the cooling passages and will cause an engine meltdown. On behalf of thousands of Volkswagen owners, please amend your advice. Thank you. -- Will

RAY: Thanks, Will. We've been told by coolant experts that long-life (organic) coolant and regular coolant can be mixed, and the only negative result will be shorter life of the coolant. But Volkswagen disagrees.

TOM: VW put out a service bulletin warning against mixing its own coolant (G-12) with its older, G-11 coolant. We'll have to take its word for it, as we're not willing to sacrifice any of our customers' VW engines to test the theory. Well, there is Mrs. Beaseley ...

RAY: So if you own a VW, it's the pink/red G12 for you. Thanks for correcting us, Will.