German Syntec in Northstars/LS1s?

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Apr 3, 2003
Toronto ON
Hey everyone. I'm looking for some insight on German Syntec being run in the Northstar and LS1 engines. Has anyone tried the oil in these engines, any feedback? My parent's car is a 96 STS with a Northstar. I've been using Mobil 1 SS in it this year with decent success, mixed 5:2 5w30:15w50 but looking for a more universal oil for it rather than mixing. I've also considered Delvac 1 5w40, despite the expense.

I've been using German Syntec in my 98 GTP all summer and have been happy with the results.
The ACEA "A3/B3/B4" quality oils are the best stuff available, regardless of SAE grade. A 0w-30 should work very well in both these engines. You may want to consider running a 5w-40/10w-40 synthetic in the older Northstar in hot weather, if oil consumption is an issue with the 0w-30.

Dixie Synthetics
I ran a treatment of Auto Rx in my father-in-laws 98 Eldorado and it helped with his oil consumption. He has 60k on it now. I would suggest a cleaning in the NorthStar. It helped him.
Oh don't even get me started on Northstars burning oil, the pride of GM and its little secret

Our first engine was replaced under extended warranty at 60,000miles after its oil consumption got to a litre every 1000 miles
Our new engine has 40,000miles on it now and its thankfully holding up much better, a litre every 2500

The engine was flushed with some GM crankcase cleaner this spring and swapped to synthetic after my dad's insistance on using regular oil started to lead to the engine beginning to burn oil again. Mobil 1 10w30 was just as bad the first use but I since learned that LS1 guys liked to mix a little 15w50 to thicken it up and so thats what I've been doing. It actually went one oil change this summer, 3200 miles or so on the Mobil mix without topping up, though it needed topping up by oil change time.

Anyhow, has there been any feedback on the german syntec in LS1/Northstar engines?

I've also been wondering if I was religious about changing the oil frequently whether GTX High Mileage (which I use on my dad's 93 TransSport and my 92 3.4DOHC Grand Prix winter beater with much happiness) would be ok in these engines?
If GM's Northstars or LS1 are "burning oil" and this is GM's "little secret", then why do you guys (especially those on this board) keep insisting it's OK to use water thin 30 weight oils and keep adding a qt. every 1k mi.?

Don't a few bells or red alerts go off? Do you guys actually think the engineers "designed" then engines wrong or is the wrong oil grade/type being used? Good luck with the 0-30...keep us posted on the consumption...
Dr.T I think the answere is "both"! Yes I think the engineers designed it wrong! Yes I think that the wrong weight of oil is being pushed!!! I think that the engineers did two things! They gave the share holders and the CEO exactly what they asked for. It is just to bad that they asked for the wrong things.

I am pretty sure the conversation went something like this. We need an engine that will be smooth, powerful, light weight, will pass emmisions and must be cheap!! Too bad they did not ask for one that would not leak oil, burn oil and was easily rebuilt!

I think that in this day and age it is perfectly reasonable to expect 300,000 miles out of an engine. I also think that the first 120,000 miles the car should not be any different in terms of functioning then it was the day it left the lot! THis is even a greater expectation when you look at the dollar amounts spent on Cadilacs,Corvets and SUV's!!

I am going to say this again for anyone that is thinking of buying a GM car in the near future. Try to buy one with the 3800 V6. It is the only engine GM has that is worth owning!!!! It only has one huge achiles heel and I am hopeful that it has been fixed now! The only problem it has is the upper intake manifold. The 3.8 does not burn oil and routinely gets to 200,000-300,000 miles before they need to be retired!
John, I agree with the 3800. Interesting when you figure out how old the design really is.

GM has a new generation of DOHC V6s coming down the tube. Wait till we see those.

My 1997 Pontiac Bonneville with the 3800 gave up the tranny after 60,000 miles. GM needed two rebuilts before I accepted as fixed. I am not tough on trannies. My 1989 Legend has close to 200,000 miles and still works fine. Thanks GM!
Could get expensive if it burns a quart every thou like my mom's Caddy. I buy 2 jugs of M1 at Wally-World twice a year, by six months and 5-6k the second one is gone.
My 1989 GMC had 150,000 with not touching the engine and transmission. My Uncles 1990 Silverado has 220,000+ and engine and transmission has not been touched. A friends Blazer had 170,000 when his trans went out. GM's are good products just like forgen cars.
Hey I might say Hondas are crap boxes because my dads 2002 Civic went through 3 transmissions in 8,000 miles! So let's start bashing crapy honda well were at it!
I'm using GC in my Northstar right now. It seems fine, and certainly doesn't need to be "thickened" up. It's a little early to tell much about usage, I think it's been in less than 1000 miles. I have only added about 1 or 2 oz. of oil to it, just because I am watching it very closely. Gas milage seems to be down just slightly, probably due to the 12.1 cst weight. The engine runs very well with it, VERY smooth and very quiet.
JohnBrowning, I usually agree with your posts in general, but I'm going to have to disagree on this one. The Northstar is a fantastic engine. It delivers over 1 HP per cu. in. and meets all pollution regs, is consumatetly driveable, and gets 27+ MPG in the process. The engine is designed to go 300,000 miles if taken care of properly. And as usual, this last one is the rub.
This engine is designed at the upper limits of conventional technology. The top ring of the piston is about 1/16" from the combustion chamber and gets really hot. It is one of the reasons "SL" oil was designed. The SL's have fewer VII to stick that top ring. Most of the problems with oil consumption in a Northstar are due to 2 things, not driving the engine HARD enough, and keeping the oil level at the "FULL" mark when cold. This engine, which holds over 7.5 quarts of oil, should only have the oil level checked when it is hot. To fill the crankcase to FULL with the engine cold starts a viscious circle of events that eventually cause the (low tension) rings to stick. Yes, some of the flushes mentioned here may help temporarily, but if the owners don't break some old habits, oil consumption will return. When I bought my used '99 it was using about 1 quart/1000 mi. I have since been able to get that down to about a quart/6000 miles....without the use of additives or flushes. If you guys really want to know about Northstars, just say the word. This post is too long already.
JohnnyG - I'd love to know more about Northstar engines. PM me and I'll shoot you my email.

My Dad has a 2002 Caddy Deville that he bought new. I'm doing the maintenance and I would be interested in any info. you can provide.

I did the first oil change at 1K with Penzoil 10W30, the second at 4K with the same oil and the third at 7200 miles with Mobil 1 10W30. We will probably go 6mos or 6K miles with the Mobil 1. My Dad is only here 1/2 the year so his car tends to sit in the garage a lot.

I agree that this is one sweet engine. Powerful and very smooth. The entire car has been a gem so far.

Glad you're happy with your Caddy ssmokn! I know I love my STS, 28 mpg with mine (trips) and will top 140 MPH before it hits the governor! No need for a PM, the best place for anyone to learn about Caddys is right here;

Just search the archives for oil usage, Dexcool, or anything else you want to know about a NS and you will be amazed. The site above, in combination with this one have been terrific sources of knowledge for me for the last year or so. Thanks to all that post here. BTW, I bet ol' JohnnyO keeps his Moms Caddy right at the full mark with all that oil....too bad.
Over on the Caddy boards they suggest #1 driving it hard (like the little old ladies will do that, yeah
) and #2 as you said keeping the oil a bit below full. I got the TSB for the engine flush for my mom's Caddy, it says you don't have to add oil until the low oil light comes on. One guy there seems to be a Caddy mechanic and suggested holding it in 2nd gear and running it at WOT to 80 mph, then let off abruptly and coast down to 55 mph and repeat a few times. This should break the rings loose from the vacuum created. I do this every chance I get
. Mom mostly putts to Wal-Mart and never gets over 45 mph but I borrow her ride to run to Syracuse, NY 1x a month at 80 or so to get my kids. I've been running Mobil 1 oil and filters in it for two years, and the consumption seems to have lessened. Picked up a K&N on the advice of the Caddy board for next week's oil change, they come down on the side of the Mobil 1 filter being too restrictive. I'll send in a UOA.

[ January 01, 2004, 11:26 PM: Message edited by: JohnnyO ]

Originally posted by JohnnyG:
BTW, I bet ol' JohnnyO keeps his Moms Caddy right at the full mark with all that oil....too bad.

Actually after I found the Caddy boards a while ago, I keep it 1/2 to 1 quart low. When I change the oil I put in 7 quarts, not the 7.5 it calls for.
While your at it JohnnyO, you might want to read some in the "air filters" section of this board. I put the K&N panel in my STS about a year ago, if I had read the stuff posted here, I would have probably looked for a Baldwin.
So, just out of curiosity, where does that 7 quarts of oil bring your level up to on the dipstick? It takes mine to the "ADD" mark, and that's where I run it. Like the man said, no need to add oil until the warning light comes on. I don't think I'll ever get that brave, since that would mean it only has 5 quarts in it. I'm glad to hear you're reading Bruce's Caddy board. Don't bother with the one where all they can do is swear at each other, that one's garbage.
I also like keeping our STS between the add mark and 1/3 up the normal range, which is roughly 7 litres. I've added nearly 8 litres in the past to get it to the full mark on the dipstick

BTW didn't see the O and the G at the end of your user names, I thought it was one person talking to himself over and over lol doh
JonnyO, I can respect every mans right to disagree! I have a low opion of the NS motor. It could have been so much more then it is!

I hope you never tear one down and then put it back together again. That engine has more little tiny gaskets then Jimmy Carter had liver pills!

It is still my opion that the best thing cadilac could do is take the Gen III block and simply improve the pistons, heads and add variable came timeing!

P.S. Thanks for the link I am going to check it!
I found this while looking at Northstar sites.


In researching this engine, we discovered that few rebuilders are overhauling Northstar V8s - not because these engines are lasting forever (they're not) but because the Northstar V8s are such expensive and complex engines. Cadillac has no reman program for Northstar V8s (if one fails, replace it with a new one). None of the major production engine rebuilders are doing Northstar V8s, and some rebuilders told us certain critical internal parts are unavailable (such as oversize crankshaft bearings). Add to this the fact that the cylinder liners can't be replaced or overbored and it doesn't leave much to rebuild.

Even the heads are throw-aways, according to Cadillac. If the valve guides are worn, Cadillac says the cylinder heads need to be replaced. The heads have hard powder metal valve guides, but we don't see any reason why the guides can't be replaced with new ones or repaired with bronze or cast iron guide liners.

Nobody said quality was cheap. The reason they're "not lasting forever" is usually, as I said before, poor maintenance. The reason the valve guides and cylider liners, and bearings aren't replaceable is because with correct maintenance, they are designed to run 300,000 miles. Yes, they are very complicated, and very powerful, and rather light, and get great fuel economy, and pass all emission standards, and will do 140 mph and make it feel like 35, and.....I think you can guess that I like mine. One other thing, the all aluminum "block" has rolled in threads, which usually are damaged when the old bolts are run in and (usually improperly) torqued. This means to replace a head gasket usually requires that the threads be time-serted (sort of a special "helicoil") they cost a BUNCH. Yes the engine is not a rebuilders dream, more like a nightmare. By the way variable valve timing is on the new Northstar engines.
Separate issue, sort of, but in Car and Driver a few months ago there was an article about guys in CA who build and run sand cars (not to be confused with VW-powered dune buggies). Picture a 4 seat sand rail (to take the kids) weighing about 2000 lbs. with an 800 hp blown Caddy Northstar in back. Another company is marinizing Northstars to put into boats. I wonder how much oil either of those burn?
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