Originally Posted by EvilTwin
Switching to full synthetic isnt a problem at all, it wont affect the warranty. The only thing about it is pick one or the other. If you go to synthetic you cant go back. Also, you should probably switch gradually. Next change, use blend and then after that use the full synth.
In the USA most synthetics are a mineral base Group III. If they were still Group IV it would not be a good ideal to routinely keep going back and forth although it would not cause any damage.