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#1342271 - 01/15/09 07:13 AM 5w40 instead of 5w30?
Spykem4e Offline


Registered: 10/23/08
Posts: 385
Loc: Montreal, canada
Hi guys! I own a cadillac cts 2005 with the 3.6l and I always used mobil 1 5w30 supersyn in it that meets the spec gm 4718m. The car has 98k miles on the odo and I'm a sales manager and I do approx. 40-50k miles a year with the car.

I do now a lot of idling with the car and if I'm not idling somewhere, I do 30-40% city and 60-70% highway. I always take very good care of my car (previous and this one) and all my cars lasted way past 200k miles without major problem.

Recently, since the past 10k miles, when idling a lot or when doing a LOT of highway driving (no speeding), the car seems to use some oil ( 1/4 quart per 1000 miles). Maybe the formulation is different than previously?!?!

My questions is this:

-is the 5w40 from Mobil 1 could be good to help the oil consumption on highway?

-Will it change something in my fuel economy? On the bottle it is written that its for turbo and diesel but my car is a regular gasoline engine with spec gm4718m for oil. In the owner manual it only required 10w30 or 5w30 depending of the weather. Will it hurt the engine to use 5w40?

-Or is there another product that meets the specs and has a very good resistance to heat?


Edited by Spykem4e (01/15/09 07:14 AM)
_________________________
2005 Cadillac CTS
3.6l v6 vvt with 182k miles
OLM OCI (10k-15k miles)

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#1342293 - 01/15/09 07:45 AM Re: 5w40 instead of 5w30? [Re: Spykem4e]
Spykem4e Offline


Registered: 10/23/08
Posts: 385
Loc: Montreal, canada
and btw, yes, there is a sweepage on the timing cover gasket, a small one that doesn't make any drop on the ground. The dealer wants approx. 1500$ to fix the gasket and I dont have time right now even the money right now to fix this..
_________________________
2005 Cadillac CTS
3.6l v6 vvt with 182k miles
OLM OCI (10k-15k miles)

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#1342344 - 01/15/09 08:42 AM Re: 5w40 instead of 5w30? [Re: Spykem4e]
sciphi Offline


Registered: 03/24/07
Posts: 8647
Loc: Upstate NY
A small leak from a gasket, you say? Um, hate to say it, Auto-RX it. Small seal leaks are right up its alley. That may just be enough to have the level drop as you are describing.

If you don't want to go that route, there's no harm in experimenting with a heavier-weight oil unless it will mess up the VVT I'm guessing that 3.6 has.
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2012 Chevrolet Cruze Eco

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#1342686 - 01/15/09 02:23 PM Re: 5w40 instead of 5w30? [Re: sciphi]
Spykem4e Offline


Registered: 10/23/08
Posts: 385
Loc: Montreal, canada
Auto-Rx it? I'm maybe to chicken to try but what would it do to my engine and/or gasket ? Is there a speacial way to use this? Can it harm the engine?
_________________________
2005 Cadillac CTS
3.6l v6 vvt with 182k miles
OLM OCI (10k-15k miles)

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#1342698 - 01/15/09 02:43 PM Re: 5w40 instead of 5w30? [Re: Spykem4e]
addyguy Offline


Registered: 09/08/05
Posts: 13458
Loc: Canada
First, I'd try the M1 High-Mileage 10W-30 to see if it helps. Bit thicker, has seal conditioners...might be just what you need.
_________________________
2003 Mazda Tribute LX V-6, 176k miles.
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#1342701 - 01/15/09 02:46 PM Re: 5w40 instead of 5w30? [Re: Spykem4e]
Smokescreen Offline


Registered: 05/25/05
Posts: 2476
Loc: Alberta, Canada
It wouldn't harm the engine for sure, but it may clean the leaking area a little more and cause it leak more, resulting in a change in seal. If that is what you want to do. Or it could clean and condition the leaking seal area and it will go back to a state where it doesn't leak.

Sometimes engines consume an oil due to its formulation. I had an engine that consumed one brand of oil, but not another.I would try a different oil brand like Pennzoil Platinum 5w30 for a couple of intervals and see if the consumption persists.
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#1342706 - 01/15/09 02:58 PM Re: 5w40 instead of 5w30? [Re: Smokescreen]
Drew99GT Offline


Registered: 10/11/02
Posts: 20893
Loc: Colorado Springs
I wouldn't go to 5w-40. I'd think that would hurt fuel mileage and not be as good for the Canadian cold weather.

Try Maxlife 5w-30. Or synthetic Maxlife 5w-30.

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#1342757 - 01/15/09 03:46 PM Re: 5w40 instead of 5w30? [Re: Drew99GT]
txrhino Offline


Registered: 11/18/07
Posts: 88
Loc: tx
If it's a gasket, Auto-RX, HM oils and so forth won't help. They may help if it is a seal leaking around a shaft, but the likely hood of it helping a gasket leak are slim to none.

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#1342794 - 01/15/09 04:39 PM Re: 5w40 instead of 5w30? [Re: txrhino]
Nickdfresh Offline


Registered: 03/15/06
Posts: 3595
Loc: Buffalo, NY
I'd use M1 0W-40 before I used 5W-40. But I second the 10W-30 HM M1 suggestion. It might not stop the leak, but it will probably reduce consumption and has a low pour point of -54F...

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#1342885 - 01/15/09 05:57 PM Re: 5w40 instead of 5w30? [Re: Nickdfresh]
OVERKILL Offline


Registered: 04/28/08
Posts: 26830
Loc: Ontario, Canada
 Originally Posted By: Nickdfresh
I'd use M1 0W-40 before I used 5W-40. But I second the 10W-30 HM M1 suggestion. It might not stop the leak, but it will probably reduce consumption and has a low pour point of -54F...


Now that we've had a few -20 (and colder days) where I have had to start the car, I concur. The Lincoln started easier at -20 with the 0w40. Not that it is hard starting with the 5w40, but it rolled faster with the 0w40.
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#1343071 - 01/15/09 07:57 PM Re: 5w40 instead of 5w30? [Re: OVERKILL]
tig1 Offline


Registered: 01/03/09
Posts: 10026
Loc: Illinois
This is not an oil issue. Google"Cadillacs burning oil". Caddys are having this problem with the north star,
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2007 Ford Fusion 147,000 miles
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10,000 mile OCIs on both engines
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#1343124 - 01/15/09 08:50 PM Re: 5w40 instead of 5w30? [Re: OVERKILL]
Spykem4e Offline


Registered: 10/23/08
Posts: 385
Loc: Montreal, canada
on my next oil change, I'll try the mobil high mileage 10w30 just to see if it helps. I'll wait til the temp raise a bit because here its like -30C so the 10w will be like a popsicle in my car or a slush on a cold start-up.

Then, if I dont see any improvement after 2k-3k miles, I'll put some Auto-Rx in it and do what I have to do. But on their website it is written that a leak could come back or increase if I use synthetic again. Unfortunately, my engne is made to use synthetic \:\(

And for the concern on those northstar engine and their oil issues, I know \:\( And the 3.6 is like the baby of the northstar so same design or almost.

For the 40 weight, I didn't think about the VVT. You are right that the weight could cause problem with the VVT.

And if I ever found 1500$ just like that, I'll made the repair! lol

Any idea of a liquid seal that is heat resistant to put on the timing cover gasket? I dont think there's a lot of pressure in the timing chain chamber so... Just for a quick fix til I found the money...
_________________________
2005 Cadillac CTS
3.6l v6 vvt with 182k miles
OLM OCI (10k-15k miles)

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#1343330 - 01/16/09 12:59 AM Re: 5w40 instead of 5w30? [Re: Spykem4e]
lars11 Offline


Registered: 12/16/06
Posts: 748
Loc: Sweden
ok, for a foreigner. What's a timing cover? Itīs not the valve cover, no?
Is it really that covered by other parts so that it will cost $1500? Can you loosen the bolts enugh to get some loctite sealer on both sides of the gasket in the leaking area?
Or maybe just tighten the bolts a bit extra? If a seepage, not much may be needed to stop or reduce it.

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#1344232 - 01/16/09 08:39 PM Re: 5w40 instead of 5w30? [Re: lars11]
Norm Olt Offline


Registered: 01/27/03
Posts: 1819
Loc: Pac NW
Uh, the "Shortstar" GM 3.5L V6 (as used in the Oldsmobile Aurora) was the ONLY "baby" Northstar unless you consider the Olds 4.0 V8 another "infant" version. Be VERY glad you don't have this engine ("Don't worry, I'll just run down to the Olds Dealership, my Dear, and have the technician diagnose the malady, order the parts and then repair the bugger under the warranty!")!!!

The GM 3.6 "high content" V6 that I know of, is available in everything from Suzuki's SUV to CTS's to an off-road crate motor...

Cheers!

Either oil will work, as would Amsoil AME, a 15W-40.
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