Well, I'm a oldie then. My dad has always used 10w30 oil. Guess I'm just carrying the tradition. Most modern car we have, a real nice silver 2001 Sunfire coupe, and we use 10w30 in the crankcase.
My 84 Citation, which has the 2.5 liter Iron duke motor, the 4 banger. It has timing gears, uses pushrods, has low compression high torque. You know those motors. I just rebuilt it a year ago, and just run it occasionally. It has regular 10w30. But right now, when the motor is warmed up, and in low idle, it has a clackey clack noise of the timing gears. Almost sounds like a diesel. It has the cheap oil because I am still trying to break it in from its rebuild. Sometime, i'm gonna try 10w30 mobil one. Might work better. Good motor though, 307,000 kms.
Anyways, love mobil one. My Buick uses it, and its ultra quiet, and runs so smooth. Has gobs of power, and its just overall a fantastic motor! Long live the 3800'* (and 3.