Yes, this is possible. This phenomenon can be compared to putting in higher octane fuel than usual. Synthetic oils are suppose to withstand higher temperatures without breaking down its molecular structure. Much like higher octane fuel, the synthetic oil in the engine could possibly create an exothermic reaction of a higher temperature. It is important to note, however, that synthetic oil makes your actual internal parts of the engine run COLDER. In fact, most synthetics make the engine run about 10 degrees colder.
Imagine a household fridge running at cold level 5/10 (higher number = colder). For he fridge to cool its insides, it must exhaust heat (just like an AC unit). If you set the fridge to 10/10 (as cold as it can), it will without a doubt exhaust even more heat. A similar idea can be occuring in your engine.
As the posters before me recommended, checking an actual measurement for temperature might help. Keep my example in mind though; the internal parts of your engine might be cooling faster and exhausting more heat
Last edited by silvab; 07-13-2009 at 01:03 PM.