I've decided to switch over to Mobil 1 Extended Performance
 

http://www.mobiloil.com/USA-English/...rformance.aspx

During the entirety of my Z ownership, I've used Mobil 1 5W30 and Nissan OEM oil filter and have done change every 5k miles (that might even be too often). But with my car being out of warranty and me being a bit more environmentally conscious, I've decided to switch over to Mobil 1 Extended Performance rated for 15k miles and/or one year oil changes.

My plan is to use EP at my next change and 10k miles later, send a sample to Blackstone for UOA (I'm confident that the EP will last at least 10k miles). Depending on the results, I will either go the next 5k miles before another change or change it at 10k (many people out there using EP are opting for an early 10k miles changes).

If anyone is curious, I will post on this thread the results later.

10K is pushing it no matter what synthetic you choose. The item i would be worried about above 5k miles would be the filter. If one of those fail it wont matter how good of shape your oil is in.

From reading experiences from other users to talking with Mobil, they say that as long as you use a high quality filter (Nissan OEM does count as one), it should also last 15k miles. Mobil also guarantees that the longer interval will not damage the engine.

Lastly, the extra protection additives in EP over regular Mobil 1 isn't just a marketing gimmick, someone did an analysis on virgin EP and confirmed that there are more additives in it over the regular stuff.

well.. try it out and let us know!

although we wont hear back from you for roughly a year... :cool:

seems interesting, how many miles does your car have now?

About 62k. The Mobil rep I spoke with said that they recommend during the warranty period that customers stick to the 5k interval using convention Mobil 1 but after that, since keeping the warranty valid is no longer an issue, EP can now be used.

They also said that they guarantee that EP won't ruin your engine with the longer interval and that the oil filter doesn't need to be changed until the oil does as long as it's a high quality filter (they said a Nissan OEM filter should be fine).