['97ventureowner]

The main reason I switched to synthetic oil was it's longer interval change. I never really considered using synthetic oil in the past,(I've been changing oil for over 25 years,) but since reading many posts on this site started to consider using it. Some members on this forum say they use an interval between 7,500 to 15,000 between changes,(changing the filter and topping it off in between changes.) Even other sites I have researched claim that specific interval change up to a year in service. What I was wondering in my post above was whether or not I got synthetic oil during my oil change, and my doubts pertaining to it by what I'm seeing with my van since the change. I want to know if I paid for synthetic and got conventional oil instead.
I'm also considering moving to a 5000 mile change interval with my other vehicles after doing more research into the matter. Engine oils produced today are much better than their counterparts in the past. They have a better additives package and can last longer. Going to a 5000 mile change interval can also reduce our dependence on oil because in effect we are using less, and there will be less to dispose of in the long run = better for the environment too. A lot of the stuff i'm reading also points to the "3000 mile change interval "as a ploy by the oil companies to make a bigger profit because we end up using more of their products by following their recommendations.
In the price I mentioned above I did include the price of the filter which was around $7.00. I believe they used a standard A C Delco oil filter, which according to many sites, including Mobil 1 is perfectly fine to do.
So what I'm really trying to find out is if there is a quick way to tell by myself whether or not the dealer used synthetic oil for my oil change, becauseI'm starting to have my doubts.