View Full Version : Cadillac NorthStar Engine?

10-19-2010, 10:23 PM
I am looking at a 1999 model boat with a Cadillac NorthStar engine. I have read as much as I can get my hands on about this motor, but looking for some personal first hand experience from a current or previous owner of this motor. Any information would be helpful. Thanks to the others that have commented on this topic through my other thread.

10-19-2010, 10:29 PM
Buddy. This is a copy/paste of a message posted some time ago. I hope it helps...

The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines. Regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal", "acceptable", "allowable", "within production tolerances" etcetera. This doesn't mean that all engines will get 1000 miles per quart (MPQ) or that the engine was designed to get 1000 MPQ. It just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

The single biggest variable and the one that haas been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher perfromance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load, high RPM operation. The Northstar engine uses a very agressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more agressive pattern than a "used" stone. So a block honed with new stones will have a more aggressive finish and most likely will use more oil.

Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax over time. All this contributes to slight bore out of roundness that is not bad or good - just different.

Carbon buildup in the rings and reing sealing are also variables that come into play with breakin, operating schedule, type of oil used, etcetera.

The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself. The single most common cause seems to be break-in or lack there of. Many, many oil consuming Northstar engines are "fixed" by some full throttle operation. We often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schdule was so light duty. The moral here is to flog it often.

In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cyilnder wall wear and the idea of a wear "ridge" at the top of the cyilnder bore is something that is laughable on a Northstar.

The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

While no one in the engineering commumnity wants high oil consuption the fact is that there is some variability in the oil consumption of an engine manufacturered at the rate of 1200 per day. The specs of what is "normal" simply reflects this - it does not imply that all engines whould get this or that somthing is wrong with and engine that gets more or less oil consumption.

There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honeing process to make it moe consistent. Changes to the piston and ring groove treatment have been made to make it more resistent to wear, poundout and microwelding at low oil retention rates. Regardless, there is still some variability.

One other thing that affects oil consuption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same - the amount added between changes is all that's different. Yet, many customers do not make the distinction. Field surveyrs repeatedly show that "acceptable" oil consumption means "not having to add between changes" - whatever MPQ that is.

The issue of oil consumption is very emotional, too, as many people perceive higher oil consumption as 'poor quality" or an indication that something's wrong. Blue smoke, fouling plugs, noise - those are signs that something's wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec. Yet it will be perceived differently.

The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It's unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption - especially as the production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

Read more at http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/8351-northstar-oil-usage.html?ktrack=kcplinkRead more at http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/8351-northstar-oil-usage.html?ktrack=kcplink

10-19-2010, 10:32 PM
Found this might have some info...


10-19-2010, 10:34 PM
Lastly, My Full Color 1999 Maristar Brochure has info on the Northstar in it.

DL the Year you would like:


10-19-2010, 10:41 PM
This is some information that I had not seen. Thank again for passing along and for the help. Just find me a boat like yours to buy and all this could end today:o.

10-19-2010, 10:44 PM
glad they worked out

10-19-2010, 11:05 PM
Lastly, My Full Color 1999 Maristar Brochure has info on the Northstar in it.

DL the Year you would like:

These brochures are great! I looked at the 1999 model year and of course it gave a glowing review of the NorthStar engine. Really cool, thanks.