The Hemi MDS motor is very sensitive to oil type used. This is NOT an engine that you can just pour whatever oil you may have laying around in and go. The intricate workings of the MDS system call for 5w-20 weight oil. This is a much lighter, thinner oil than what was used in American V8 engines until recently.
Most people will find sticking to the manufacturers recommended oil weight is best in the engines. If you vary much you’ll have trouble and may even have costly damage from the experiment. The question as to whether to use synthetic or not is less black and white. If I were going to keep one of these engines “forever” then I would certainly use synthetic, although I doubt it would make a tremendous difference in longevity, it would help some. The main thing after determining type of oil is keeping up with maintenance and getting the oil changed on time! You can read some discussions about oil choice in these engines HERE.
One of the best things you can do to keep your Hemi MDS lifters happy is pick a good oil and filter brand right from the beginning and change your oil and filter regularly. Dirty oil causes wear to internal components. Once tolerances become too large between pieces due to wear, noises start to become a problem.
If you find yourself in need of purchasing Hemi MDS lifters we can help! We have sold top quality lifters since 1996.