The dealerships excuse for not using synthetic oil is laughable. I bought a new G37 sedan from our local dealership a year ago and they insisted I come in for my 3 month oil change when the car was 3 months old. I told them that it only had 900 miles in the first 3 months, but they wanted to change it anyhow. Because the first change was on them, I took it in and had it changed. I have always changed my own oil on every car I have ever owned, but this was free so I let them do it. I thought that maybe the valve clatter noise on cold start-up would deminish after the oil change, but it didn't. I changed the oil myself at 4000 miles and used Penzoil Ultra synthetic, but the lifter clatter is still noticable for about 20 seconds at start-up. I'm sure this is common to all G37's, and nothing to get excited about. This is probably the wrong thread to post the lifter noise, but does anyone else have the same noise at start-up? I plan on staying with synthetic and I myself will change oil every 5000 miles.

 

As it has been stated before there should be no legitimate reason to not use synthetic in these cars. However, I would be cautious on changing over to synthetic after using regular for quite some time, I have read this is where possible issues can arise, but I don't remember specifics. If you plan to use synthetic I would start with your first oil change.

IMO the only reason these engines don't require synthetic yet from the factory is the lack of direct injection. Any other German makes and even the domestics using DI require synthetic now and more and more cars use it standard, I was surprised to hear Infiniti doesn't use it, but then again they also think your oil change should be every 3,000 miles. If you switch to synthetic even with hard driving every 5k is perfectly acceptable. Shoot..bmw is only doing changes now every 10k.

 

If the noise is only on cold starts and not on warm starts, it isn't valve or lifter clatter. It is a different combustion profile to warm up the engine and cats. You'll see that the noise corresponds to changes in rpm that are also part of the programming. The amount of time it takes is directly related to how cold it is (inverse to temperature).