So I recently bought my (2004) with 75k and did the routine oil and plug swap I usually do when I buy a new car, I used conventional oil as I the car had full service records from a local infiniti dealer including oil changes and I figured thats what it had used. So at my next oil change I decided to use a dino blend oil, well I had to change the oil a little early due to a road trip/vacation and after 2500m I burned a full quart vs the 1/4 quart I burned with on the first oil change with conventional. My plan is to do a change back to conventional at about 1500m and another after another 1500m to help combat potential sludge build up from the switch from dino to conventional . So I'm looking for a little insight and opinions on how to handle this as I'm out of warranty and don't want to pay for a new engine. I'm hoping switching back to conventional will help with the oil burning but I'm slightly unsure so any recommendation would be great.

 

Just quit switching back and forth and go with a full synthetic oil like Mobil 1, your G35 will appreciate you're doing so. With Mobil 1 and a Fram filter you can buy at Wall Mart change oil/filter at 2K miles twice and that should clean out the dino residue then you can go with change intervals every 4K miles. This might fix your OC issues!
Gary