We have a 03 DeVille with 92,000 miles on it. I recently had the oil changed at Jiffy Lube, when the odometer read 89,500. Here a couple of weeks ago my wife said the "check engine oil light" came on. It took 2 qts. of oil. There are no spots in the garage or driveway when her car is moved. Is this normal for these engines to eat oil like that? Is this a common problem with the Northstars? Any suggestions what to do for a fix?

Your first problem is Jiffy Lube. Did they know, or charge you for, about 7.5 quarts of 5W-30 ? What has your past oil consumption been? The "Check Oil" light comes on at 2 quarts low, as you found out. Best to maintain the oil level at halfway up the hashmark on the dipstick as a Northstar tends to throw out that first half quart pretty quickly. Go down to Northstar Performance and read up on how to do a WOT (Wide Open Throttle) run in order to free up piston rings and clean carbon from the piston/head quench area. Run a few tanks of Shell, Chevron or Texaco gas. Run a 20 oz. jug of TECHRON with a gas fillup. Google "techron" and "top tier".

Read the Technical Archives in the top ^^^ black bar. A consumption of 1 quart per 1,000 miles is not unusual, but still high, in a Northstar.

Your first problem is Jiffy Lube. Did they know, or charge you for, about 7.5 quarts of 5W-30 ? What has your past oil consumption been? The "Check Oil" light comes on at 2 quarts low, as you found out. Best to maintain the oil level at halfway up the hashmark on the dipstick as a Northstar tends to throw out that first half quart pretty quickly. Go down to Northstar Performance and read up on how to do a WOT (Wide Open Throttle) run in order to free up piston rings and clean carbon from the piston/head quench area. Run a few tanks of Shell, Chevron or Texaco gas. Run a 20 oz. jug of TECHRON with a gas fillup. Google "techron" and "top tier".

Read the Technical Archives in the top ^^^ black bar. A consumption of 1 quart per 1,000 miles is not unusual, but still high, in a Northstar.

Yes they charged me for 7.5 qts. I checked the receipt to see how much they did add and what the mileage was when I changed it. It also was the middle of last month when we had it changed.

WOT her
wide open throttle
go to tech archive for more info
http://www.cadillacforums.com/cadillac-tech.html#noil

WOT? My wife knows nothing less than that. That is normal driving to her.

beating the piss out of the car and performing a WOT are entirely different
you must put the car into 2nd nail it to redline and let the car power-brake itself back down to speed

I'm going to bet that they charged you for 7.5 quarts but only put in 5. That would make a whole lot of sense here. Not to mentions it's a very common thing with those guys. Also remember that up to 1 quart every 1000 miles is considered normal.