In regards to the not depending on the service light. Dodge owners manual for my 09 RAM recomended it be changed at 6K miles and I would have likely done that however the light came on around 3K so it was done then. Only once did I ever see the light stay out for near 6k miles or 10K kms. I'd say based on my experience that the light is more cautious than the recomended service intervals outlined in the book. BTW.. When it comes to grade of oil, especially with the HEMI make sure you use the recomended weight. If you use a more heavy you will have troubles. Something to do with a small hole the oil needs to flow through? Something to do with timing maybe? Can't recall exactly but it's all related to ticking in the engine. (which I had but it was the header bolt not the known "Hemi Tick").