0w-40 or 5w-40 in GM LS1 04 GTO?

[why2kmax]

Hi guys, Ive done a search and havent quite found what Im looking for. So Im asking for opinions, fact or just plain help.

I have an 04 GTO, LS1 with 11,500 miles on it. I used M1 5-30 per GM to about 9500 miles, then switched to M1 0w-40. Its been in for 2000 miles or so and the motor is a bit quieter, runs smoother. I like it so far. Oil analysis coming at 3,000 miles to be sure however.

I switched to 0-40 as it seems to be a better oil, and the 5-30 looked a bit thin. Oil analysis on the 5-30 showed no real abnormal problems other than normal break-in. High copper and silicon but they said that was normal for an LS1 under 15,000 miles, thats it.

My question is would the new M1 5-40 truck/suv oil be a good sub for M1 0-40 for my car.

0w-40 is hard to find around here. Only autozone carrys it and sometimes pep boys and its always 5.50+ a quart IF they have it. This 5-40 would save me about $10 an oil change vs the cost of 0-40 not to mention the hastle of finding it. Wally world has this 5-40 M1 by the cases in 5 qt jugs for $20 and singles for $4.50

wondering if it would be an acceptible substitute for M1 0-40. I worry more about wear as it is my daily driver and I log about 25-30k a year and I intend to drive this car until the wheels fall off. Motor is stock and is likely to only be lightly modified with bolt ons if anything

If Im reading the tables right..

cst vi at 40/ and 100c/ VI / HTHS
5-30 40c 56 100c 10.0/ 175/ 3.08
0-40 40c 80 100c 14.3/ 187/ 3.6
5-40 40c 103 100c 14.8/ 151/ 4.1

but Im not sure how the additive pkgs differ or if it would be too thick to use year round.

any thoughts?

 

[buster]

quote:

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Its been in for 2000 miles or so and the motor is a bit quieter, runs smoother

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Any of the above are absolutely fine for your engine. In fact even M1 5w-30 has shown good results in the LS1. Not the best or most consistant, but pretty good.

I would run the 0w-40 to at least 5,000 miles. If it were mine and I were using Mobil 1, I'd use Mobil 1 Extended Performance 5w-30/10w-30 or the 5w-40

 

[SSDude]

The 5w-40 M1 Truck and SUV should work very well. As Patman has pointed out the LS1 needs a heavy 30wt or a 40wt. The M1 0w-40 is really a medium/heavy 30wt. I plan on running the M1 Truck and SUV in my LS1 this summer and plan on doing a UOA so that I can compare it to GC.

 

[bighead]

I'd stay clear of the 5w-30. After noticing how much smoother and quiter my meager 3.4L Grand Am engine ran when switching to GC, I won't use the M1 again. At least not in that weight. GC should work great in that engine. Just a suggestion

 

[TooSlick]

I'd run the 5w-40 for the six warmest months and then run the 10w-30 the rest of the year....

The 10w-30 will actually pump easier than the 5w-40 down to about 0F, due to the shape of the viscosity/temp curves for each oil....Note that even at 40C the 5w-40 is still almost twice as thick as the 5w-30 and about 66% thicker than the 10w-30.

TS

 

[Shannow]

Recommendation per Mobil (OEM fill) down here is

"MOBIL 1 10W-30 or MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40"

with

" If MOBIL 1 10W-30, MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40 is unavailable, may use MOBIL SUPER XHP 15W-40 or MOBIL SUPER HP 20W-50."

 

[haley10]

quote:

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Originally posted by Shannow:
Recommendation per Mobil (OEM fill) down here is

"MOBIL 1 10W-30 or MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40"

with

" If MOBIL 1 10W-30, MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40 is unavailable, may use MOBIL SUPER XHP 15W-40 or MOBIL SUPER HP 20W-50."

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In the USA, GM specifically recommends Mobil 1, 5W-30 Super-Syn. It's a vehicle specific recommendation.

 

[why2kmax]

quote:

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Originally posted by haley10:

quote:

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Originally posted by Shannow:
Recommendation per Mobil (OEM fill) down here is

"MOBIL 1 10W-30 or MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40"

with

" If MOBIL 1 10W-30, MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40 is unavailable, may use MOBIL SUPER XHP 15W-40 or MOBIL SUPER HP 20W-50."

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In the USA, GM specifically recommends Mobil 1, 5W-30 Super-Syn. It's a vehicle specific recommendation.

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I wonder if the the thinner usa reccomendation is for CAFE and MPG reasons more than anything else. An LS1 in the US should use the same oil as one in australia, at least spring through fall. Winter may be a bit different depending on how cold it gets, but I cant see why the different oil for the US when the aussies been running the heavier oil in the holdens forever.

Thanks for the replies guys. Every bit of info helps.

 

[Mitch Alsup]

"0w-40 is hard to find around here."

Without knowing where "here" is:

It is somewhat well known that the LS1 engines like a 12 cSt oil for best wear characteristics. This corresponds ot a thick xW-30 oil or a very thin xW-40 oil. M1 is a rather thin xW-30 oil.

Unless you have a particular driving condition to satisfy (like track use), an HTHS number of 3.6 is sufficient. From the oils you listed, I would prefere the one with the 80 cSt startup viscocity (and 3.6 HTHS) than the 100 cSt (and HTHS of 4.1).

 

[Ryan00TJ]

My LS1 below showed the best wear numbers running Schaeffer 15W-40 Blend. A mix of 10W-30 @ 15W-40 Schaeffers' was close behind. The car is usually run very hard and the sample with the 15W-40 had close to 30 track runs to 6800rpms on every shift. Now that I have exhausted my Schaeffer's oil stock I plan on running M1 5W-40 TSUV all year. I want and need the higher HTHS for my driving conditions. Since my LS1 is gargaged all year I don't worry about cold weather starting.

 

[Win]

quote:

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Originally posted by haley10:
It's a vehicle specific recommendation. [/QB]

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It's not in the owner's manual for my '04 GTO. GM6094M is the only specification.

I run Havoline synthetic 10/30 in my 2004 Goat. There are things that keep me up at night, but this is not one of them ....

 

[Volvohead]

My age (from being around engines too long) tells me to go with the 5w-40. But my head tells me either will be just fine in that engine year round. The 0w might move a little quicker at start up on the very coldest days, though.

 

[Racerjk]

I run 0w40 in my LT1 Formula and T&S in in my wife's GTP. I can't speak for an LS1 or LS2, but I love both of those oils!