Cooling system additive in Ford 7.3 IDI ?

The additive is still required to prevent cavitation damage to the engine. All anti-freeze has some protection but, not nearly to the level required to protect a Diesel engine. This additive also has to be periodically replenished independently of the antifreeze to maintain a proper level of protection. Heavy duty truck dealers have inexpensive test kits to be sure the proper level is maintained. You might check a Navistar dealer since Navistar actually built this engine and used it in many of their medium duty trucks and busses. This is just one of the joyful little maintenance quirks of a Diesel that owners of gas burners may never know.

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:

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

Hope this helps......

I'd do some research over at

I doubt that your truck is supposed to be using that coolant to begin with. If it is supposed to work, it may have the additive already in it.