1996 Infiniti I30 white smoke

I have a 1996 Infiniti I30 and I have noticed that if I let the engine run for a while white smoke starts coming out from under the hood. It's not heavy smoke but a medium amount of smoke. I check the gauges and it says the car is not overheating. Tlhe smoke seems to be coming from the back part of the engine I would say probably in the middle or closer to the driver side. any help with why my car would be smoking but not overheating.