[Richard and Rhonda]

Clarke,

Here is a good place to start. http://www.etrucker.com/apps/news/article.asp?id=47234

To quickly answer your question, you can buy test strips at your local truck supply place to check the nitrate levels. If they are low, there are two ways to raise them. One is to change the coolant filter, and replace with a filter that contains a nitrate booster. The other is to buy the concentrated nitrates from the truck supply house.