The latest issue of the RV Daily Tips newsletter has a short article about the value of an engine monitor gauge such as the Scan Gauge. Although the article doesn't mention it, there are other gauges in addition to the Scan Gauge, and we have discussed them quite extensively on this board.
http://www.rvtravel.com/?q=daily-rv-tips-issue2609182
The newsletter is free, fun, and informative, especially for people who enjoy RVing but are not mechanical experts. And just for the record, I have no connection to RV Daily Tips, RV Travel, or any of the gauge companies.
Bill