I contacted Havoline technical support today to ask if their Havoline Pro-RS Lifelong Full Synthetic oil is similar to a High Mileage oil since they advertise this oil as having seal conditioning agents just as they do on their High Mileage oils. Their reply: "The RS is a different base stock and does not use the esters as the high mileage oil/" I further asked if the seal conditioning agents in the Pro-RS oils would have a swelling effect on engine components such as O-rings, gaskets, and seals and this is what they said: "The seals will not know what oil you are putting in. Modern oils do not rely on seal swell agents. The synthetic base stock works differently. Modern cars engines using modern oils do not require seal agents. The seals are made better also." On Havoline's web site regarding the Havoline Pro-RS Lifelong Full Synthetic oils that will be sold exclusively at Walmart, there is an article that clearly states that this new oil is an addition to the High Mileage oils except that the new RS type can be also used on new cars. Something does not add up. When I asked the Havoline rep if the new RS oil was just a rebranding of one of their other oils, I received zero reply and was completely ignored. What are your thoughts on this new oil? Is it really just a different full synthetic oil or a high mileage oil or maybe a combination of the two? I did not fully understand the Havoline's rep answers and ended up just as confused as before I started my chat with him.