I have a 99 STS with 105,000 miles. It was leaking some oil and found a stripped head bolt. This was fixed and now it uses oil (about 1 quart every 600 miles. Replaced the PCV valve and it uses a little less. before the repair it used maybe a quart every 3,00o miles. Also the mileage has dropped off from about 25 average to 20. It also has stalled 3 times in the last few weeks when I lift off the gas when coming to an intersection. Any comments on how to research this? Thanks
:yawn: If good ol' Destroyer is lurking, he can take my quote from Post #32 and slide it up here, 8.3 months later. To date, in order to maintain the oil level at halfway up the hashmark, I have added 12 oz. of Pennzoil Platinum 5W-30, and this covers a round trip to CT and another to OH, all highway. No coolant. 3 runs to 132 mph (GPS).
I did a code check and got some codes B1983, B1344, B1652, B1760, P1599, P1617 and U1064. The ones that seem most critical are P1599 Engine stall detected and P1617 Engine oil level switch circuit. What should I do next?
ehanso, All your codes are benign. Clear them and drive the car. Establish a code history, then begin a new code thread. Remember that when you clear codes the system needs 2 weeks of normal driving to settle out in order to pass an OBD emissions test.
I just reached 4,000 miles since my HG project, and I realized I had not checked the oil since then. I was surprised to see I needed to add 2 quarts to get the dipstick back up to 1/2 way between add and full. The low oil message never came on - neither did the low oil pressure. I suppose 2 quarts in 4,000 miles is pretty good at 100K+ miles - everything on the engine is original, except for the head gaskets and bolts and the other gaskets and seals I replaced during the project.
Took a bit of digging, but this is the perfect thread to share this tidbit............
GM TSB #02-06-01-009C of Oct. 23, 2003 gives quite a rundown on Northstar oil consumption, reasons, fixes, and combustion chamber cleaning. Well worth the read.......maybe one of our techs can post the entire thing....it isn't too long, BUT there are two points that bear repeating and which will raise a lot of eyebrows:
1. The current GM accepted oil consumption figure for a maintained moderate-mileage Northstar engine from the 1996 - 2003 year group is 2000 miles per quart.
2. If the oil level is at the MAX mark, or close, on the dipstick, then the engine is a half quart overfilled and the PCV system will rapidly scavenge the excess oil by sending it to the intake manifold to be burned. (This alone may lead to perceived high oil consumption.)
If you can't wait, subscribe your car to www.alldatadiy.com and read the TSB section. Eye-opener. Actually, anyone who has arrived since mid-2007 should read this entire thread - both pages.
Errr... My Northstar 2000 SLS with 135,000 is asking for a quart in 300 miles after a couple years of a quart every 1000 and a quart in 2000 back at 80,000 miles. I have "exercised" it... going to try 4 quarts of DELVAC and some more exercise.... I'll update you after that.
Holy smoking tail pipe Batman. Now THAT"S oil usage. Can't help but wonder if you have some other underlying problem.
History has shown the 4.9 to be the superior overall motor as compared with the N*. It's funny to see 4.9 owners state that there cars are not "N* powered" as a selling point when they sell their cars.