engine oil is it better to use High Mileage oil full synthetic, or High Mileage conventional, or full synthetic?

Hello! A full synthetic oil provides longer protection to your engine than a conventional oil will. The synthetic oil resists breakdown better than conventional oil so it can provide longer lasting protection to your engine. High mileage oil has different additives in it that are supposed to help the seals of your engine be flexible and maintain their sealing capabilities. No matter what type of oil you use, it is extremely important to change it at the manufacturer recommendation. With a full synthetic oil, most manufacturers recommend a 5,000 mile service. Keeping your oil clean by servicing the oil and filter is the best way to help your engine run without metal-on-metal contact causing damage internally. If you have further questions, let us know!