Well maybe thats a little over the top but heres the story......
Got my 02 xterra in super clean shape with around 57000 miles. It had a fresh oil change using amaco dyno oil when I got it. So finally hit 59500 miles and decided it was time for a change. My dad uses shaffers oil which is supposed to be better than any synthetic oil on the market(some private brand stuff here in MN) anyways I was getting 14ishmpg even on the highway and today I rechecked after 2 weeks of driving with synthetic and even with the ac on 24/7 I came in at 18.5mph. Is this normal to see such a huge improvement? I was thrilled and curious if anybody else had good luck changing over?

I bought my 05 X 3 months ago - new. It needed some warranty work at the time it was due for an oil change. I asked the dealer to do the change and to use synthetic. They said that Nissan does not reccommend using synthetic oil until after 10,000 miles. When I get past the 10,000 miles I will be switching. I hope to see the same results. I average 16mpg - air on - air off - in town highway - it does not seem to matter.

i switched to synth around 7500 oh well

I put Syntec in our new 05 X after 2000 miles. I've read lots of posts on various sites with reasons to and not to change the oil to synthetic early, and have decided to do it anyway. I figure, with the break-in period, there'll be a fair ammount of metal shavings liberated and since I have a lead foot, I don't want those circulating around if the RPMs go to high, causing the filter to go into bypass mode. In my car (2003 mazda 6), I've been running fully synthetic oil and tranny fluid for the past 25,000 miles, and am very impressed with the smoothness of shifting. I also saw an increase in milage, but think most of that's due to my CP-E CAI.

Man, I just wish I could get at least 14 mpg. I've been using Mobil 1 since I got my '01. I'll be switch to the same thing in my '05 on the next change.

I switched to Mobile 1 in my 05 at 15K. There is no difference in MPG, and I didn't expect there to be. I did it just as a piece of mind. I have been chaning it every 5K and since I started changing my own oil again, it's not costing my any more to run synthetic than it did to run dino and have someone else change it.

I hate changing oil that is why I always paid someone to do it. Then I got the Shrock bumper w/ skid plate and the first time I took it to get the oil changed it came out of the garage dripping oil. They just took the filter off and let the skid plate fill up with oil. After that I said screw it, the 15 minutes that it takes to change the oil is better than having to try and clean out the skid plate after someone else does it.

I am currently getting no beter than 16mpg Highway and about 13mpg city. Averaging about 14mpg.