cadillac northstar oil choice

[sfam198]

My step-dad has a 98 Eldorado with the 4.7 Northstar engine. He is seriously one of the worst people I have ever seen when it comes to car maintenece. He used to drive the car every day 1.5 miles to and from work (3 miles round trip) with the occasional highway trip (maybe once every 2 months or so). Despite my telling him that the oil needed to be changed extremely frequently, he would change it maybe once a year if that. Luckily his new truck has an OLM and I've gotten him to start following it (he used to ask me just to reset it when the message came on the dash but I refused, now he just asks me to change it). With the same driving habits he had with the Cadillac, the truck tells him to change it usually within 1500 miles or so.

Anyway, back to the car. Due to his lack of maintenece of any kind (although he won't listen to me when I tell him that), he managed to crack the block at 42,000 miles (I believe he ran the radiator completely dry and drove around for a few days like that). Cadillac wanted upwards of $9,500 to replace the engine with a brand new one with 3 year warranty or some such. Him being the tightwad that he is, asked a buddy of his to get and engine and replace it. Well, he got hosed on that job too (although he won't admit it...guy charged him $3,500 to put in a junkyard engine with something like 130,000 miles on it). So now he has a 98 with an engine with 130,000 miles and an odometer that says 43,xxx. Don't even get me started on the odometer fraud, I've already tried to explain it to him, he doesn't want to hear it.

Well, the "new" engine that was put in leaks and burns oil at a rate of about a quart per month. I've told him to take it up with his "buddy" that dropped the engine in, but he doesn't want to confront him about it for fear of messing up their friendship. Whatever

He won't pay someone to take a look at the engine and find out why it leaks and burns oil, and I'm sure not going to take the time to do it either, when I know that he's not going to do anything about it.

My question is...what oil should I put in this thing to minimize the consumption as much as possible? I know that at this point, nothing is going to stop it, but I want to minimize it so that on the off chance that I actually get him to start changing the oil on a somewhat regular basis, I haven't already dumped 3 quarts into the engine for make-up.

The car gets driven maybe 200-300 miles a month now that he has the new truck, so I am thinking of just going with 6 month changes with a thick (20w-50) Maxlife or something. Maybe some HDEO 15w-40? I know when he does drive it, it hardly ever gets up to temp. so I'm more interested in the cold viscosity than anything. The engine specs 10w-30, so I don't think a thicker oil would be too detrimental to it. And quite frankly, if he doesn't care enough to have the engine properly fixed, then I don't really care enough to put something decent in it. I just want to patch it up enough to the point that he'll stop complaining to me when the "low oil" light comes on. At that point it's about 3 quarts low (7 quart sump), so I don't think that it'll be impossible to get consumption down to less than 3 quarts in 6 months.

Sorry for the long read, but I figured I should include a little bit about what I'm dealing with here, plus I just had to vent a little bit.

Thanks in advance for the help.

 

[mdocod]

NorthStar engine have a notorious issue of plugging up the ring packs. They have a bizzare ring-pack design. These engines would actually be better off if they were driven like race cars from the day they were drove off the lot, but the problem is, they get driven like Cadillacs. (slow, easy going, people who own them never tap into that engine). By running them slow and laxidaisy for years, the rings plug up, stop seating properly, and burn lots of oil.

These engines are built really well, and could easily see 300,000 miles or more with proper care.



My recommendation is that you "barrow" that car from him.. (trade cars, or something). Pull the plugs, do a MMO or seafoam (or something like that) soak over night, something to get he cleaning started up top. crank the engine with the plugs out to blow out the excess, re-install plugs. Run it for a few miles to warm it up, drain oil. Start an ARX treatment following the instructions on the site. Drive it like you stole it through clean and rinse cycles. Do a second treatment if you can. Again, driving it like ya stole it.

 

[sfam198]

hmm...wasn't aware of the issue with the ring-pack design. that's probably where most of the oil burning is coming from then. as for the leaking, that's another story.

he's definitely not an easy-going driver, his right foot is always to the floor wherever he goes.

borrowing the car is not really an option right now, for other reasons. but i could probably talk him into doing a MMO soak and then start an ARX treatment. Is there a time limit to how long that needs to be done in? With the amount of driving he does, it would take forever to get through both treatments. I could tell him to drive it more often, but both he and I need our trucks for work, so it's kinda hard for us to drive the car every day.

 

[mdocod]

The ARX can stay in the crankcase a month or a year, running time(milage) is the important thing. The engine needs to see plenty of running time at operating temp. 1500 miles with the ARX in, then 2000 miles "rinse" with plain oil, since you are having leaks, do both clean and rinses with a very conventional plain dino oil, something like supertech. ARX is sometimes able to clean up and help the oil do it's job at reconditioning seals, sometimes it works, sometimes it doesn't either way, it's good for the engine. A lot of those seal leaks may have been from the engine sitting "dry" in a yard for who knows how long.

Start with the upper cylinder soak, keep in mind, that oil usage may actually increase after the soak if the cleaning is not complete, this is where ARX comes in. But if the oil consumption CHANGES (more or less) after the soak, then you know it has something to do with crud in the rings, if it stays the same, then that may not be the issue. So start with a soak and go from there. IMO any engine over 100,000 regardless of history and condition, can benefit from ARX.

 

[sfam198]

ok, that sounds like a good plan. i've used ARX in 2 of my own trucks with excellent results, so i'm familiar with how it works. i definitely will use some plain old supertech (I always do with ARX) and we will see what happens.

 

[Steve S]

Wouldn't touch it with a 10 foot pole.