Originally Posted by davidjb

I believe 0-30 is better suited for freezing weather and is unnessarly thin this time of year.I just changed to Castrol Edge 5-30, it meets the specs for the turbo engine and claims 8 times the wear resistance of Mobil 1. Its expensive though, 35. for 5 quart bottle at walmart. it also claims 15000 mile oil change which I would not do........

Originally Posted by MGMsHHR

I had Mobil 1 0-30 in my 2.2 cobalt and my 2.4 hhr all winter. It did seem to crank better when it was cold. I got it at wal-mart for $26 which was a 5 quart container. The 2006 Cobalt has 10k on it and the 2008 HHR has 22k. Could not really see a milage difference but starting the cars and let them warm up kills gas mileage........

Originally Posted by Hib Halverson

Any "5W30" is an "SAE5" viscosity at 0° F and a "SAE30" viscosity at 212°F.

The GM Ecotec four cylinder engine family is designed for an SAE30 engine oil when it's at 210° or so. The 5W part of the oil, aids in easier starts in extremly cold weather, ie: 0°F or colder and it aids in very slightly increasing fuel mileage when the oil temp is below 212 but above atmospheric.

In the early 1980s as a way to "kiss butt" to the Federal Government and as a way to incrementally increase the fleet average fuel econonmy of all its vehicles, with a few exceptions, GM has recommended 5W30 engine oils.

To make a multiviscosity 5W30 oil, Mobil Oil and other companies blend "viscosity index improvers" into engine oils. The "VI" improvers are what give petroleum-based and synthesized-hydrocarbon based oils their multi-viscosity properties, but VI improvers have no lubrication ability and they break down under very high temperature.

At higher oil temperatures, which a small four-cylinder engine without an engine oil cooler, such as an Ecotec, will sustain on a regular basis, a 5W30 is not as good an engine oil choice than a 10W30, because it has more VI improvers which can degrade lubrication. This is main reason I always suggest a 10W30 unless the duty cycle is regular operation in very cold weather.

As for what oil to use, well...that depends on how you drive your HHR and how much you want to spend.

The best engine oils, regardless of price, are ester-based synthetics. Red Line, the brand I use, is one of those.

The Mobil 1 brand is a large family of synthetic lubricants marketed by Exxon/Mobil Corp. The Mobil 1 engine oil distributed widely in North America is a synthesized-hydrocarbon-based synthetic, which is certainly better than a typical mineral oil, but not as good as an ester-based synthetic. Ester-based synthetics typically have very little or no VI improvers. Red Line 10W30 has no VI improvers. Red Line 5W30 has a very slight VI improver component which is much less than that of petro- and synthesized hydrocarbon based oils.

Bottom line on engine oil for your 2.2 or 2.4 Ecotec if the duty cycle is "normal".

Ok: factory-fill or equiv. petroleum-based 5W30.
Good: petro-base 10W30
Better: Mobil 1 10W30
Best: Red Line 10W30.

As for who really needs a 5W30? If you not just start, but operate your HHR in temperatures which are below zero most of the time, then you should use a 5W30 petro-based oil or Mobil 1. If I operated my HHR in weather that was zero or below quite often, I'd probably be using Red Line 5W30.

But....that's not the case. My HHR "lives" in southern California so I want better protection and lubrication at oil temperatures beyond 212°F, thus I use a 10W30 and an ester-based one at that.

I think ester-based synthetics are a better choice in extremely cold weather, too, as they do not have as much of a viscosity increase at temps below 32°F. I've run Red Line 10W30 in temps as low as -20°F. and have had no trouble with starting. This is because while it's an SAE10 at zero, it's still close enough to that at -20 that cranking RPM does not decrease much. Try that with a petroleum-based 10W30 and the results might not be as good.