Which oil for my "new" 2006 Monte Carlo 3.9L?

[mstrjon32]

Hello all, I recently purchased a GM Certified Used (with the cool new 5 year/100K powertrain warranty) 2006 Monte Carlo 3LT, with 9400 miles at the time of purchase. I drove the car until about 10050 miles with the fresh dino oil that was in there (the OLM indicated 29% life remaining, but I think the service guy just forgot to reset it), and then changed it out for Mobil 1 5w30 and a Purolator PureONE filter. Sadly, the Ultraguard filters which I'm so fond of are no longer available in the UPF-61 size, so I went with the PureONE as a second choice.

Prior to signing back on to BITOG, my plan with this car was to just follow the OLM (with my current driving, I'm headed for about a 2500-2800 mile interval! -- no I'm not beating it, I'm just taking lots of short trips, that will all change in a few months, though), and stick with M1 and the PureONE filters. However, I'm now reading that M1 is a synthetic blend, and while I'm sure it's still a good oil, I wouldn't mind going with something fully synthetic, especially if it can be found at a comparable price. My second choice would be Castrol Syntec; I've also heard alot of people mention the Pennzoil Platinum, and I'll save this as a final choice, for some reason I'm just not too keen on it.

So, with that said, what oil would you all recommend for this complicated (as far as I'm concerned, with it's fancy VVT and piston oil-squirters) new 3.9L engine? I would like to stick with the OLM as a reference for changes, for both warranty purposes and it seems to be pretty accurate. I do plan to keep this car for at least 100K miles, and if it holds up like my 1997 Monte Carlo did, right on up to 200K.

Any input much appreciated.

 

[Merkava_4]

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However, I'm now reading that M1 is a synthetic blend,

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Mobil 1 just can't get a break. . .

 

[vronline]

M1's not a syn. blend... it's supposedly a Grp III oil, although I'm not sure if anyone has been able to prove it definitively. If you've had good luck with it in the past, I'd be content to keep on using it.

The other oils (Castrol Syntec, PP) that you mentioned are very good as well. I'm find the one that you can get easily for the best price on a consistent basis and run it.

 

[Thatwouldbegreat]

Just run Mobil 1 5w30 or Pennzoil Platinum... or any other properly rated name brand synthetic 5w30.

Change with 5% to 0% left on the OLM and save receipts.

 

[Alan]

That's a nice engine you got there man,lotsa grunt.

I'd run dino and change it at 50% of the OLM.

 

[JohnBrowning]

If M1 has truly gone to useing GIII then their is currently no fully synthetic oil at the retail level. M1 was the last company useing GIV and V base stocks! All of the others have had GIII in them for years! I would stick with your current routine unless a UOA indicates it is not doing a good job!

 

[Patman]

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That's a nice engine you got there man,lotsa grunt.

I'd run dino and change it at 50% of the OLM.

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The OLM in that car would've been calibrated based on the assumption that people are running conventional oil, so you can safely run it down to 0%.

 

[98LSC32V]

My friend has the same engine in his 06 Pontiac G6 GTP... it impressed with with it's all around torque. He uses Castrol GTX 5w30 and changes it when the OLM reads 10-15%.

 

[dave1251]

Any SM conventional oil 5w30. Use your OLM. Then get an UOA every so often. Like once a year or two. You Monte Carlo will die of an rust/wreck/or you no longer like it. Before the engine dies.

 

[mstrjon32]

Thanks for the replies guys. I think I'm just going to stick with my current strategy then. I knew something was up with the M1 formulation, I just didn't know what it was. I'm not 100% sure what the difference between a Group III and a Group IV or V is anyway (I think one is based on crude and the other two are synthetically formed from the start...), but as long as its still a good value for money I'll keep using it. I think M1 oil is a good fit for this engine; it's not crazy enough to warrant something really expensive, because with all the fancy electronics and variable-ness aside, it is still a reliable GM pushrod.

dave1251, you're probably right, but my old one (which I still have, I'm debating if I should hold on to it or pass it on) has suffered from a stuck lifter as of late, and the rest of the car is in otherwise pretty good shape (despite having little things break on a non-stop basis, which is what prompted me to buy the new one). Since I bought this car almost-new, I'd rather just spend the extra money and have the piece of mind of synthetic. Especially once I move back to the northeast (I'm living in Oklahoma right now), I think it will make cold morning starts much easier and reduce wear.

98LSC32V (and Alan), It is quite a nice engine, lots of grunt all throughout the powerband. The only thing that doesn't make any sense to me is why GM decided to put such a gas-guzzling final drive in this thing. Its turning just a touch slower than my 3100 at highway speed, and is making a mountain more torque. Regardless, if you step on it, it really pulls hard; the biggest problem is the 4-speed automatic. I actually test drove a G6 GTP 6-speed with this engine before buying the Monte Carlo, and I loved the 3900/6-speed combination; unfortunately I hated everything else about the G6. I'm just a large coupe person I guess.

 

[98LSC32V]

A little off topic, but my friend has the 4 speed auto in his GTP. Would have been sweet if it and the Monte Carlo came with a 5 speed auto. Mobil 1 5w30 is not as good as it used to be, they changed the formula for it. I would use Pennzoil Platinum 5w30, it's cheaper and just as good as the Mobil 1. I'm switching from Mobil 1 next oil change.

 

[mstrjon32]

Yeah, it's not even that I mind the automatic (though I do prefer manual; although I have a feeling the target Monte Carlo customer does not) it's just that the 4 speed really leaves you hanging for passing power if you're crusing around 55-60mph and decide to overtake. If you just want to cruise around someone, no big deal, the 3900 has plenty of torque to push you along, but if you really want to fly around a truck or something, it kind of falls on its face. If you're doing 75-80, though, and step on it, it really throws you back in your seat and takes off like a rocket towards 100. Unfortunately, having all the power way up there really isn't as useful unless you're doing primarily long-haul interstate or turnpike driving. I'm curious to see what kind of pull this engine/transmission combination has upwards of 100 mph, but its very infrequent that I get a chance to play around at that kind of speed; next time I'm driving across I-8, I suppose. But, I digress...

As for the oil, I picked up the Mobil 1 in a conveinient 4-quart jug (the 3900 takes 4 quarts, which seems like an awfully small amount, but maybe I'm just used to older engines) for just under $23 at my local Advanced Auto Parts. I also saw the Pennzoil Platinum, but it was only $3 less so I figured I'd go with the M1. I don't remember the exact price of the Syntec, but I think it was about the same as the M1.

 

[Steve S]

Use any non syn. oil.

 

[mstrjon32]

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Use any non syn. oil.

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Is there a good reason besides cost why you think I should use conventional oil over synthetic?

 

[Steve S]

The engine doesn't need syn oil . What is expected from the syn oil, there will be no magic. Look in the uoa section at the wear numbers that are posted . If syn oil is not required there will be really no "real" benefit to run it.