Why this question will probably never be answered correctly is because most people just give their own opinion without any real proof of what they are saying. When you ask the question “how long does synthetic oil last” the first problem is what brand are you referring to? There could very well be the exact same oil in two different bottles and one manufacturer will tell you 5,000 miles and the other might say 7,500 and this is why there is no definitive or correct answer within this industry.
The other big problem when trying to figure out how long does synthetic oil last is you don’t always know if you are getting a pure synthetic oil even though the brand you bought says synthetic on the label. In fact most synthetic oil on the market today comes from a class of base stocks known as Group III, which are a form of highly refined petroleum oil. It’s not fair to a successful synthetic oil manufacturer like Amsoil to be playing on an uneven field.
When you invest in Amsoil Synthetic Lubricants we tell you exactly how long your oil last and with our wide range of options you can choose from three different tiers. Take a look at our homepage and see what drain interval best suits your needs. Drain Intervals
Some of the best information you can learn from are from technical data bulletins and nobody other than Amsoil does a better job at presenting this information on all their products. Take a few minutes and look over Amsoil’s specs on their top of the line motor oils.