Will synthetic engine oil help to keep my RV longer?
Generally, yes, however some with some qaulification. Synthetic oil by itself will not completely protect from engine wear. Not all synthetic oils are equal. You would want a 100% synthetic lubricant that is manufactured in conjunction with oil and air filters and has been developed based on an oil analysis that gives the breakdown of contaminates. (Similar to a blood sample from your own body would).
Air and oil filters that remove contaminants beyond the run of the mill products will keep the engine oil cleaner longer but the additive package in the 100% synthetic lubricant allows longer servicablity that petroleum oils. These oils have a form of parafin and hydrocarbons that are more of an insult than a help to reducing friction in an engine with temperatures in access of 400 degrees.
The drive train also needs something better than what petroleum can offer. Synthetic will provide that without question.