Kirk in Iowa wrote:
I switched to FULLY synthetic oil some time ago. Use it in my wife's Murano too. I used to change the oil at 3,000 miles with dino oil, but changed that to 6,000 with fully synthetic. I use Mobil 1 fully synthetic. And yes, oil sellers are allowed to say "synthetic" even if it isn't fully synthetic, so be careful.
I always change oil myself...been doing that for the last 35 years, so paying big bucks to have the oil changed isn't a issue. Mobil 1 is about twice as much as a good dino oil, but a double the mileage, who cares.
A good (not necessairly popular, but good) oil filter is necessary regardless of what oil you are putting in.
Check out this web site for more info, and be sure to check out the post above in the stuck thread area about changing your own oil...it is very well done.
I used to use synthetic in all my engines, but a lot of testing from Blackstone shows that Castrol GTX DINO in many engines (VQ series Nissan for one) outperforms the Mobile-1 Synthetic. That's the regular synthetic, not the 7500+ ones. For the record, I just switched to Castrol about 7 months ago, prior I was using Amsoil or Castrol Syntec European Formula, but I still got nervous running much past 4k miles so I'd change it anyways, and that's not cost effective.
At any rate, I just change my DINO oil every 2,500-3,000 miles. I know people who run synthetic and go 10k miles, but I worry more about the oil filter in those cases.
Plus after a year you may need to add more oil, etc.
Anyways, I say save your money and get Castrol GTX and just change it every 3-4k miles.
On a final note, any of you who claim it "feels" smoother are full of crap. That's just placebo effect and your brain trying to justify 3-4x the price of oil.
If you do want to run synthetic, run AMSOIL as it truly proves itself in oil tests.