Options for Cadillac DTS with the Northstar Leak

[Ddub]

Hi Guys,
I purchased a 2009 Caddy DTS (with about 45K miles) from my grandfather about 2 years ago and noticed it had a mild oil leak. A little research led to the fact that it is pretty common for these engines and that it is VERY expensive to have it fixed because of the large amount of labor required. Noticing that the current fill at the time was a little low (7.5 qt sump) I topped it off with a little M1 5W-30 (the recommended oil and what was in it a the time) and a can of LM Oil Saver. After few hundred miles, the oil leak was still present, but noticeably improved.

I ran that mix for about 3K miles, and then changed the oil to straight M1 5W-30. The oil leak returned to its former state within a couple thousand miles and I thought that adding more Oil Saver might overfill it, so I just left it alone for a 5K miles total run.

The current fill is Pennzoil Platinum HM 5W-30 with no additive. That slowed down the leak very slightly but not as much as when I was running the Oil Saver with the M1. Once the oil has cooled to ambient temperature, it stops leaking, but definitely puts some oil on the ground while the oil is hot.

The PPHM has been in for about 5K miles, and I will be changing the oil again between now and Halloween. Without buying anything new, I have at my disposal the following options that would work in the Caddy:
- 5 qts M1 0W-40 (which I understand is now kind of a heavy 30wt / light 40wt)
- 7.5 qts of PPHM 5W-30
- 1 can of LM Oil Saver

I was thinking about running the PPHM with a can of Oil Saver in order to further quell the oil leak, and change it every 7K miles or so with a can of Oil Saver every time. Do you think this is a sound theory or would you recommend a different course of action? Thank you for your input.

 

[CELICA_XX]

I would skip the "oil saver" and just use a good HM oil.

Valvoline MaxLife Full Syn 5w30 would be my choice.

 

[crazyoildude]

My northstar leaked from around 40,000 miles so i used Pennzoil high mileage 10w30 and it cut it down to near nothing i would never use a synthetic in there i tried once and it leaked very badly.. I used Valvoline Max life last time and it was ok but this time i will be using Mobil High Mileage just because i have a couple of 5 qt containers from my son.

 

[nwjones18]

I can tell you my STS leaked with both M1 and Maxlife. Have Castrol Magnatec 5w-30 blend in it now and no more leak for 1.5 years...

 

[Chris142]

Those engines are garbage.dont forget that it needs stop leak in the cooling system too keep water out of the oil

 

[slacktide_bitog]

With a large sump and an oil leak, you might want to try something cheaper. There's still time to stock up on Napa Synthetic for only $2.99/qt. Napa also sells the motor oil saver you're already using.

Maxlife is also supposed to be a very good HM oil, and it also meets dexos standards.

 

[BobsArmory]

YES, Valvoline Maxlife (Red Bottle) is a blend and it's much cheaper AND since it's a DEXOS approved oil it meets all requirements for your car! It's a win win in my book.

In Texas the 10w-30 version would be perfect for your application since it never gets super cold.

If you want to give the high milage oil a little extra kick, try a product called ATP AT-205 on Amazon Amazon Link I have used it in the past and it really does work. Many people here have used it and swear by it.

 

[901Memphis]

Yep ATP205 actually works great. I first tried the motor oil saver and it helped some but the atp 205 worked so well that I hardly smell burning oil anymore in my Altima.

Moved up to a non full synthetic 10w40 and that will help too.

 

[nwjones18]

Originally Posted By: Chris142
Those engines are garbage.dont forget that it needs stop leak in the cooling system too keep water out of the oil


This in an unfortunate but common opinion of these engines. My family has 6 different Cadillacs with Northstars of varying ages and none have had headgasket issues and a couple have had over 200k miles on them. The later models didn't have the same issues, and the RWD version had none of the stereotypical N* issues either.

 

[Ddub]

Thanks, guys. All good options to consider. I may buy a 5qt jug of the Dexos approved Maxlife (5W-30 or 10W-30) and combine that with the 2qts of the open jug of PPHM 5W-30 I have leftover from the last change. No sense in wasting the PPHM and I don't think it is going to harm anything. I have some solace in the fact that when the car sits undriven for a few days, that no (or extremely little) oil continues to leak past the point of the oil cooling down. It seems to only be leaking a bit when the oil is hot/warm if that makes any sense.

 

[purelux]

Originally Posted By: Chris142
Those engines are garbage.dont forget that it needs stop leak in the cooling system too keep water out of the oil


You must have done about zero research for that false information. The leak which is not in a high % vehicles of has nothing to do with a gasket simply failing which a seal tab might work on. It is the head bolts with being too fine and short amount of threads which are also torque to yield. The factory pulled the recommendation of seal tabs and to discontinue doing so on vehicles which had it listed in their maintenance. The leak also does not normally leak water into the oil it gets exhaust gas into the coolant. Often requiring a block test kit since it doesn't have a tell tell obvious contamination of the fluids. They went to a longer threaded bolt in 02 then in 04 to a coarse thread virtually eliminating the problem.

 

[TheLubinator]

You might want to try a 5w40 or 10w40 to slow that leak on one OC as a test, I'd also go with a dino oil and just change it every 5k or less.

I was told when I had my 1995 Deville that the Northstars were prone to losing more oil with a synthetic, something about the aluminum block being a bit on the porous side and the oil tended to "sweat" through. Don't know myself, I always used dino on her.

-The Lubinator

 

[dwendt44]

IIRC, I remember that Oldsmobile with this engine had
a tendency to leak at the oil cooler lines.


My 2¢