Automania/Repair & Maintenance

AUTO QUESTIONS AND ANSWERS FOR WEEK 51

by Bob Hagin

Q. I have a 1995 Cadillac Eldorado with the Northstar V8 engine. There is 25,000 miles on the odometer and in the last 3000 miles, the engine has used four quarts of oil. There is no evidence of an engine oil leak under the car as there are no drips on the garage floor. The Cadillac dealer says that this is normal oil use for this high-performance engine. Could this be possible? Please advise me as I know that there are many Cadillac owners who have the same question. R.S Mukilteo, WA

A. A quart of oil every 750 miles is too high and I'm really surprised that a Cadillac dealer would dismiss your complaint so casually. Cadillac is striving to keeps its place in the crowded luxury car market and I've been told by its P.R people that it's bending over backwards to not only retain its aging customer base but get into the auto psyche of American Baby Boomers. High oil mileage complaints are often countered by the comment that it's within "acceptable limits" but those limits are set arbitrarily by the factory and sometimes by the factory rep who is investigating the problem. At one time, one of the American auto makers told their dealers that 500 miles per quart was "within limits." A disgruntled mechanic sent me a copy of the memo which I still have. I'm sending your letter on to the Cadillac public relations department for comment but in the meantime, tell your dealer (in writing) that you want to have your Cad inspected by a factory rep. Please let me know what happens.

Q. Initially my 1990 Oldsmobile gave me good gas mileage. However in the past year I noticed a drop in it. Also my car whines when I drive slowly or when I use the brakes. The front brakes have been replaced in the past and recently the rear brakes have been worked on, too. It also makes these noises on the highway. The mechanic put this car on the diagnostic machine but could not find anything wrong. Please advise me as to what I can tell my mechanic to look for or what you suggest can be done with these problems since they bother me. H.J. Norfolk, VA

A. It's impossible to diagnose noises by mail. Take your mechanic for a ride under the same conditions you encounter when you experience the brake and chassis noises. Tell him or her that those are the noises that you don't like and that you want fixed. If the repair is undertaken, immediately go for another road test to make sure the job is done right. The fuel mileage problem will take some sleuthing on your part. Totally fill the tank, travel a predetermined number of miles using your trip meter (100 is a good number), refill the tank to the same level, and divided the miles traveled by the exact amount of gas used. Repeat the process a couple of times and give the results to your mechanic. Unless a diagnostic machine is used in conjunction with a dynomometer that simulates real-world driving, it can't find complex road-load related problems. Like any tool, a diagnostic machine is only as good as the technician that's using it but be prepared to pay for the time involved.

Q. I recently finished restoring a '72 Fiat Sport/Spyder. I didn't rebuild the engine because it runs fine, is peppy and has good compression on all four cylinders. After it has been sitting a day, a cloud of blue smoke comes out of the tail pipe. After running for five minutes, the smoke goes away. The longer it sits, the bigger the smoke cloud and the longer it lasts. W.D. Walnut Creek, CA

A. It sounds like oil collected around the valve stems when you shut down is leaking past the stems and collecting on the pistons. You could pull the cam covers when it's warm to see if the oil drain-down system is plugged, too. Change to a different oil brand and viscosity and the problem may go away but remember that oil is cheaper than an overhaul.