It's like Lugnut said. .... without the additive cavitation can occur which
is basiclly eating up the block etc.

The test strips are relatively inexpensive, very easy to use and I consider
them cheap insurance for a very expensive engine. The additive is not
terribly expensive either.

Here's a link to where I get mine:
http://www.dieselpage.com/motorfw16.htm

they are a good co. to deal with, and no, I have no affiliation

Hope this helps......


> wrote in message
oups.com...
> I recently puchansed a 1994 Ford F250 IDI non-turbo . The previous
> owner
> just changed the water pump about 6 months ago and flushed the cooling
> system and replaced with ( gold color ) Prestone Extended Life
> antifreeze at %50 dilution but didn't add in the any of the cooling
> system additive ( called FW16 in the owner's manual ) . Is this OK with
> this kind of
> antifreeze or do I need to put some in ? - thanks
>