Originally Posted by RAMitDOWN
If your truck is still under warranty wouldn't increasing the interval be a problem ?
No because dealers realize that synthetics don't break down (lose their viscosity) as quickly as conventional oil. Some mfgr's recommend or require synthetics in some of their engines, like my 6.1L HEMI in the SRT8.
Now, they won't decrease the interval on my Chrysler just because it came with, and continues to be filled, with 0W-40 synthetic. It still gets regular changes every 3K miles. As long as you regularly service, and check, your vehicle's lubrication, no warranty issues should arise.