I just purchased a new 2013 FX 37 and was surprised the dealer recommended having the oil change at 3700 miles. I came from a long line of European cars, VWs, Volvo, Mini and they all at least go 6,000 to 10,000 miles on synthetic blend, but I always change the oil myself and go fully synthetic and change the oil and filter every 6,000 miles.
Questions:

1. What type of oil do the dealers put in the car during the 3700 mile oil change - reg oil, syn blend or full syn?
2. If I continue to change the oil myself and go 6,000 miles and have the receipts to prove it , will I still be covered by Infinity warranty.

thnks

Pull out your owner's manual to see what type of oil is recommended for the FX37. You should be okay with conventional oil at a 5k interval. Modern engines simply run a lot cleaner these days and even conventional oil is cleaner and has the ability to handle a 5k change interval. If you decide to go with synthetic oil a 7k change interval would be okay. Just check your oil level at 3k miles to determine if your FX is burning any oil. Importantly, don't be a cheapa$$ and just get your oil services done at Nissan/Infiniti.

thks, I decided to follow the "less severe" maintenance schedule in the owners manual, which means taking it in every 7500 to the dealer for oil change and service, but I change the oil my-self with Synthetic oil somewhere in between and rotate the tires. Like you said, you can get extended run times when using synthetic oil. Personally, I like to change oil every 5 or 6,000 using synthetic oil.