The oil is a synthetic blend. I changed my oil in my 06 to a synth blend and got a very small rear main seal leak immediately after its first short run. I cant get conventional high mileage all the high mileage where I live is fully synthetic plus I wanted to change to 10w 40 which I couldn't find in conventional anyway!
I live with the small leak as my TJ motor seems to liked the 10w 40 in our winter. I bought Castrol Magnatec at half price so got enough for another change, I will early change in November when it starts to warm up here but I may be going 10w 50 for summer so might keep the spare 10w 40 for start of winter change.
If the leak bothers you change it to a conventional high mileage, the cost of oil and time to change it is peanuts compared to the bee you will have in your bonnet if you cant find the leak. There is no sump plug washer on the 06 might be the same for all TJ,s? and if it is from spillage it wont dribble down for long once the engine gets hot a few times.
I have owned Triumphs most of my life so oil leaks dont bother me, the colour of the leak lets me know when its time for an oil change