We had a 12/1 "thumper" and a 24/2 unit set up with the glowplugs out in our yard this past winter. Morning temps were -10 and we left the engines outside for a couple of hours to get "acclimated" to the cold. After applying the glowplugs to both units for about 20 seconds, both fired with relative ease and we were impressed with the results. We tried the plugs, again on a couple more occasions and are satisifed that if they engines will start in the middle of a Maine winter, they will start anywhere. Give 'em a try; I am sure you will be pleased.....Thanks, Phil from Central Maine Diesel