QuestionI have a 1997 suburban 2500 with the 7400 engine. I now have 45000 mile on it. My question is, why has this engine, from the start, consumed up to a 1/2 qt. of oil everytime I go on a trip doing highway miles? I've changed the oil every 2500-3000 miles. No blue smoke comes out of the exhaust and underneath the engine is perfectly dry - no oil leaks. I'm the type of person who checks under the hood very frequently so it's never run low but it's always bothered me that with a new vehicle I've not been able to drive between oil changes without having to add oil.I'v had other GM V-8s and have never had this situation. One case is a '87 Pontiac safari wagon with 160000 mile. I still have this car, use it for local driving and it's never used oil between changes.
My intention was to keep my Suburban for the long term- 150-200,000 miles but I'm concerned that this engine may not be reliable for the long term. Is it time to cut my losses and unload it while it still has some trade-in value??
Hope to hear from you with your opinion. Thanks,Tom
AnswerHi Tom - All I can tell you is my experience with this type of thing, and let you decide.
We have had one 454, in particular, that after about 65,000 miles, started burning oil. Now, one thing you don't tell me is how much the truck is burning inbetween oil changes in total. GM states that something like more than about a quart and a half inbetween 3000 mile intervals is too much. This particular truck we had was using lots. Make a note as to the mileage, date, and the amount of oil that you add for awhile. This gives you something to look at.
Anyways, we ended up putting a brand new engine in this truck, as it had extended warranty. I would try going to www.allddata.com to see if they show any bulletins, or recalls on your problem. Then take the bulletin number down to the GM garage and have then look up the number to see if it applies to you. I received brand new rotors and pads on my Malibu because of Alldata!
Have you done some troubleshooting to see if you can tell where the oil is going? Rings, intake manifold? You probably would not be able to see the oil being burnt in the exhaust down the highway, as we could not with the one we replaced the engine in.
If you have done the troubleshooting, done the Alldata thing, and spoke to your local GM garage about helping you out with this, (I think it is a bit more of a problem than we realize, but no one has come out and said anything), then I think you are right it letting it go. You do not want to be putting a motor into a truck like that at this stage of its life, and this is very unlike GM motors. I have had about fourteen of them already, and only my first one used a quart between oil changes, but never more than that. While I think of it, my Dad's 94 350 did that too.
But, if you are using about a quart to a quart and a half between changes, it is a bit unusual, but not unseen. Record the consumption for awhile to make sure you are doing the right thing, and maybe you can get some satisfaction out of GM if it is using more than normal.
If I can be of any more help, please feel free to drop me a line.
Automotively yours,
Dean
