The only way you're going to be able to tell is if you go back to non-synthetic and see if you have the same result with your engine. Just be aware that there are a number of factors that lead to oil consumption; such as heat, atmospheric temperature, type of driving and viscosity of oil to name a few. I'm sure you're aware of the numerous threads on oil consumption in some 3.8's, not all. Not to debate it but I only use non-synthetic oil in this engine because it's not engineered to specifically run on synthetic like, for example, BMW's, Corvettes, and even Mini Coopers, etc. In those vehicles I only used synthetic. It's like using premium fuel in it. It's not made to run on it. It's actually more important to change it more often with this engine to get rid of contaminants then to extend the oil changes using synthetic. The tolerances just aren't there in the manufacturing process. The 3.8 is a good engine and will last but it will never be a performance engine which would require different types of maintenance. In order not to further debate it and help you I'll go back to change out the syn. and see what happens. It's only one oil change.