Thoughts on GC in an 06 4.6 rwd Northstar?

[TTopJohn]

Partly for the sake of simplicity since I like to run the same oil all the cars, partly because I'm convinced it's an excellent oil, I'd like to run Castrol Syntec 0w30 "GC" in an 06 Cadillac SRX with the 4.6L Northstar. This is the LH2 rear wheel drive / all wheel drive Northstar variant, used in our SRX as well as the STS and XLR, with variable valve timing on both intake and exhaust cams as well as some other changes from the tranverse mounted FWD Northstars.

GM factory fill is Mobil 1 5w30. A few other oils are listed to meet the GM spec for this engine as well, but GC is not among them. Working on the theory that GC will nearly always be able to sub in for Mobil 1 5w30 with no ill effects, I'm guessing it will be no problem to use GC in this application. I like the 0w30 weight of GC because I think it flows quicker at colder temps, and I like that GC is actually a thicker oil than M1 5w30 and thus should provide more than adequate hot weather protection as well.

If anyone else has thoughts I'd be happy to hear them. Thanks.

 

[SuperDave456]

GC is known to be a thick 30 weight. Even though it has that "0" in there, that only counts if you are getting down well below freezing. The first number has practically nothing to do with thickness at room tempature, and everything to do with actual pour point.

I'm in Dallas also, and I am thinking that you will be just fine. Especially during summer months where it is triple digits for months. The high for today is 76.
As long as you stick to a synthetic "30" weight in that engine I dont see you having any trouble.

 

[jldcol]

With the info in the OP, are you saying the GC you want to use does not meet the GM specs for the engine? No warranty worries then?

 

[tig1]

Why not just use the oils spec'd for your engine?

 

[TTopJohn]

I'm considering departing from the factory spec for two reasons:

1) I think a thicker 30 weight like GC offers more protection than an average to thin 30 weight like M1 5w30, while still staying within the spirit of the factory 5w30 weight recommendation. Further, GC's additive package has performed well for extended (6000 mile) oil change intervals in my 740iL, which is also a 32 valve 8 quart capacity variable valve timing (on one set of cams) DOHC V8.

2) for convenience - I already run it in the Camaro and the 740iL, if I run it in the Cadillac I only have to stock one oil.

Warranty is a small consideration, but I don't anticipate any failures that could be linked to use of GC. It seems unlikely that a Sythetic 0w30 that is actually thicker than the factory spec Synthetic 5w30 could cause any harm. As opposed to some oils I would be concerned to use in an engine spec'd for M1 5w30, like say a 5w20, 10w30, 10w40, 20w50, or a non sythetic oil etc.....

 

[TTopJohn]

If you're curious, the oil Cadillac calls is anything that is both 5w30 and GM4718M. They specifically warn against using "10w40 or 20w50 or any other viscosity grade oil not recommended"

 

[sparkplug]

Synpower is GM4718M approved. So is Q-Horsepower. Both of them are excellent oils.

 

[BullyT]

Hmmm....TTopJohn and you own an '01 740 so I'm going out on a limb and thinking "This must be JohnG" off a very popular BMW website;-).

I use GC in my '99 740iL and also switched my Ford Explorer (SOHC 4.0 litre engine) over to it a couple of years ago. The Explorer is spec'd for 5w30. For as long as I'd owned the Explorer, it had a rattle from the camchains at low speed under acceleration or load. Ford actually replaced the engine under warranty....and the new replacement did the same thing. With GC in it, the engine is definitely quieter and always starts easily in cold weather (north of Torono). With your hot temps in Texas I think the heavier viscosity of GC is a good thing.

Better cold weather flow and a little higher viscosity in hot weather makes GC a good choice IMHO.

 

[addyguy]

As long as you're fine with voiding you warranty requirements (with the trouble GM is having, they would probably use any and all excuses to get out of a warranty repair, EVEN IF the repair is not oil-related) then you'll be fine - as you say, GC is a good oil.

Not sure I would do it, though! If it were me, I'd go with the new Valvoline Synpower that is 4718m cert....

 

[Steve S]

As cheesy as G.M.is warranty wise . Use a recommended or rated oil.

 

[TTopJohn]

Originally Posted By: BullyT
Hmmm....TTopJohn and you own an '01 740 so I'm going out on a limb and thinking "This must be JohnG" off a very popular BMW website;-).



You got it TTopJohn is my older Camaro-centric handle. From a few of the oil, UOA, etc.. discussions that have gone on over there, I'm guessing you are Peter.

Thanks for the thoughts everybody, I still haven't quite decided what to do on this but all of you have raised good points.