I have a 2001 Pontiac Sunfire 147k manual tranmission, low oil pressure light comes after drving for about 10-15 mins or when the oil temp get above 195. The light only comes on when I drive really slow or idling. Also i've noticed when I don't apply much pressure to the accelorator the engine makes a noise or at the very low low end of each gear I hear the noise. What could be wrong?