Pontiac Repair: 2005 Pontiac Grand Prix, pontiac grand prix, pcv valve

Question
Hi, I have a pontiac grand prix, and recently, I have gotten the low oil signal from the idiot box for the first time.  My question is; my mechanic tells me that a 2005 pontiac grand prix with 65k miles, it is normal for the engine to burn off a quart and a half of oil for the last 8k miles.  That was the last time I had the oil changed.  Is this normal? My mechanic couldn't find a leak under the car.  I do a lot of stop and go traffic everyday, and I bought the car new. To me is seems like a lot of oil to be burning, and to be honest, it is the first time since I was a kid I've had this problem.  
Tell me please if you think this is normal.

Answer
Hi Michael:

Yes GM states that a quart of oil in 2,000 miles is an excetable amount of oil consumption. every engine burns oil but in small amounts. If they didn't "use" oil the engines would seize up and the cylinder walls wouls be scored up and it would use way more amounts of oil. It's is a bit odd that all the sudden you noice it. A few things to check would be if the car has an aftermarket pcv valve put in it that can cause an increase in usage. Also as the engine get older and miles on it they wear and will use more oil. The fact that you do a lot of stop and go traffic that will have an effect on it as well. So bottom line is this is NOT using an excessive amount of oil. Just keep an eye on it. I'm not a firm beliver in the engine oil life monitors on the cars I'm old school change the oil every 3 months or 3,000 miles which ever comes first. that in for conventional motor oil. If yusing synthetic you can go longer say 5,000 miles but no longer. One last thing if this is using oil do not switch to synthetic it will increase the consumption! Good luck :0