I have had this car for 16 months. Until july it never leaked oil, not a drop. I have been experiencing a loud clattering sound when it is first started for the day, at around 1500 rpm, which quiets down once the car is throughly warmed up. There are differing opinions on this, possibly some pre-ignition, or the hydraulic lash adjusters are plugged/have too high a leakdown rate/or affected by low oil pressure. As a result of the advice given I switched to GC 0w30 in july, and after about a week I began to see a few drops of oil on the floor. I made sure everything was tight, but the drops continued. I have ramps and observed an oil coating on the entire engine pan, and on the oil filter, and around the flywheel. I have read that some seals can be affected by a group 4 synthetic, I am hoping that is what is going on. I have just changed the oil to a dino 5w30(4pm, saturday, nov.29/2008), 6 litres with 12 oz of auto-rx. I first heard of auto-rx on the cadillacowners forums, and have been curious to try it. The car now has 70,500 miles, before I bought it was dealer maintained and I have the records. I usually change oil every 3 months, even though I don't drive more than 7000 miles in a year. It is all short city trips, with one annual trip from Toronto, Ontario to Moncton, New Brunswick. I get 28.5 miles to the imperial gallon (4.54 litres vs 3.89 litres for the american gallon i believe) on the highway. I will be making a point of adding weekend day trips to get the necessary milage in to make proper use of the auto-rx. I will add updates regarding (i hope) any reduction in oil leaks, if the clattering is affected, and if the mileage increases.
Now at 72,000 miles, engine is much quieter, with the clattering almost non-existent, there also seems to be more pep. There appears to be just one spot the oil is leaking from instead of two. I changed my driving style back to being somewhat aggressive on the gas to help clean out the carbon. I was experiencing a 'cold carbon rap' in addition to the clatters. After several months the rap is no more. I have noticed the oil getting dark and idle sometimes not smooth so will be changing the oil filter soon. 1500 miles to go for the rinse...
-- Edited by CobaltBlueSTS2003 on Saturday 11th of April 2009 03:43:02 PM
Glad to have you. If you want go to Google and type in "Northstar Engine" quite a full disclosure. I am familiar with rear main seal leaks on the Northstar. Please read how Auto-Rx stops seal leaks (if you have not already)
Make sure to stay with non synthetic oil. After your done with complete Auto-Rx Application. DO NOT ADD ANY MORE AUTO-RX just drive for up to 3000 miles and see if leak has stopped.
Auto-Rx cleans the front & back of the seal material (no swelling) and we use "simple" additive package in non synthetic oil to restore pliability. (initailly your leak will probably get worse as seal is flabby) hope this is of some help.
