I need to get an oil change and i was thinking of using synthetic for the first time. Is their ever a time when its too late to start using synthetic oil? I only have 44,000 miles on my 98Gt and i was told that the rings have adapted or worn in to only conventional oil. If i started using that they (people at auto zone) said that synthetic oil would mess my motor up by allowing oil to slip passed the rings and burn oil. In my latest issue of MM&FF there was an article on oil. It seemed like you could interchange the two at anytime. Is this true? Is there a benefit of synthetic over conventional and which grade/weight(ex. 5w-30) is the best for my car? Thanks in advance!!