I have an '06 G35 that since around 90K has had pretty loud valvetrain tick/knock and general top end noise when hot. I attributed it to the abuse the car takes on a daily basis. I have run M1 0w-40 since new - except for some track days. The oil temps in the car cruising on the highway floats around 115-125C typically, higher if I am over ~4.5K for extended periods of time. during track days it was hitting 160 w/ M10-w40 and also M1 15w-50. It hasn't really gotten any worse in the last 70K. Oil temp (in this car) seems to be related more to engine speed than load.
Yesterday I got home and (because it was almost 100 degrees outside) I left the car running with the AC on while I detailed the interior. I realized after an hour or so that the engine was totally silent - like it is when cold. I hooked up my scan tool to see if anything was significantly different than normal. Other than excessively high air (70c) intake temp, the oil temp had dropped to 82C. I went out and got on the highway for a few miles (highway here is ~85mph typically), came back home, the tick/knock was back. Let the car idle for another hour while I washed the outside if it and detailed the exterior, leaving the scan tool connected. The noise subsided around the time the oil temp dropped below 90c. At 90c it was just audible, by the time it dropped to 85 it was totally silent again.
So. I've been ignoring the noise that makes my car sound like a broken tractor for 70K miles. If I were to go to a thicker oil, potentially quieting the top end noise, is it likely that something in the bottom end would be unhappy?
When I used to do a lot of track days I used M1 15w-50 and still had the tick/knock, but the oil temps were significantly higher.
The next model year increased HP and RPM and many people added a secondary oil cooler (I think Nissan sold one for them). The newer ECU would also limit RPM after the oil got to a certain temp. The newer motor also had variable valve lift which apparently really increased oil temps and noise in the valvetrain.
Should I just continue to ignore it or would it be worth trying something thicker? The lowest temp this year was around 40F. It will be 95+ for the next 4 months.
Yesterday I got home and (because it was almost 100 degrees outside) I left the car running with the AC on while I detailed the interior. I realized after an hour or so that the engine was totally silent - like it is when cold. I hooked up my scan tool to see if anything was significantly different than normal. Other than excessively high air (70c) intake temp, the oil temp had dropped to 82C. I went out and got on the highway for a few miles (highway here is ~85mph typically), came back home, the tick/knock was back. Let the car idle for another hour while I washed the outside if it and detailed the exterior, leaving the scan tool connected. The noise subsided around the time the oil temp dropped below 90c. At 90c it was just audible, by the time it dropped to 85 it was totally silent again.
So. I've been ignoring the noise that makes my car sound like a broken tractor for 70K miles. If I were to go to a thicker oil, potentially quieting the top end noise, is it likely that something in the bottom end would be unhappy?
When I used to do a lot of track days I used M1 15w-50 and still had the tick/knock, but the oil temps were significantly higher.
The next model year increased HP and RPM and many people added a secondary oil cooler (I think Nissan sold one for them). The newer ECU would also limit RPM after the oil got to a certain temp. The newer motor also had variable valve lift which apparently really increased oil temps and noise in the valvetrain.
Should I just continue to ignore it or would it be worth trying something thicker? The lowest temp this year was around 40F. It will be 95+ for the next 4 months.