Cadillac Repair: Seville motor noise, cadillac seville sls, cadillac seville

Question
Dear Bill,
I have a Cadillac Seville SLS 2000 with 50'000 miles. Oil consumption is about 1 liter for 2'000 miles. Recently I had a special loud noise (a kind of sharp knocking of the engine) when starting the engine (after a rainy night). I checked oil and found it in the middle of the marked section (consistency/smell looked fine to me). When re-starting the engine the noise came again but disappeared after about 30 seconds and everything was fine for the whole day. But on the next day the same again and I added about 1 liter of oil (up to the upper mark). Since then no problems anymore. However, this combination of oil consumption and noise worries me. Further, I would like to replace the high mounted 3rd brake light. Do you know a dealer in the USA who sells this light and would also ship it to Switzerland (payment by Visa credit card)?
Thanks for you help, Francis


Answer
Hi Francis, Oil consumption of 4 liters in 1,000 miles would be cause for concern. The first thing to do is make sure there aren't any external leaks. Get the oil and filter changed. Then after the engine has sat for 2 hours remove the dipstick and add oil to the full mark. Then drive the car while monitoring the oil level. When it gets 1-2 liters low then add oil and make a note of the mileage and how much was added. Then after 3,000 miles if you needed to add more than 6 liters then there is an oil consumption problem. The Northstar engine has a problem of the piston rings getting carboned up and then the engine will start to use oil. What is recommended is all the sparkplugs be removed and 4 ounces of special cleaner that removes carbon like top engine cleaner or sea foam be poured into each cylinder and let soak overnight. Then disable the ignition coils so they can't spark and crank the engine to get the liquid out. Then install the plugs and enable the coils and start the engine and then drive it until the smoke clears. It will make ALOT of smoke so don't start it indoors. You may need to do this 2 times to get the rings unstuck.
As for the engine noise it would be best to get it to a shop so a technician can hear the noise and its location to determine what needs to be done. I am surprised that 1 liter of oil low would make a noise.
The third brake light should be no problem for any bigger Caddy dealer to order and send. I would use Google to search for Cadillac dealers or use the yellow pages of a search engine to find a dealer in a bigger city. If you need me to give you some names and phone numbers then let me know. Hope I have been of some help. Bill