I have a 2006 HHR LT. Owners manual states to use 91, however I have been using 87 with no problems....Should I try/Switch to 91 ?

 

Performance is a LITTLE better with 93/91 and milage is a little better with 93/91. If you are happy then no worries!

 

X2

I've been using 87 almost exclusively. I'm getting about 24 mpg back & forth to work. (20 min drive each way about 7-8 miles)

 

Actually the 2.4 is a "premium optional" engine. That is the OM recommends 91, but also says you can run 87. You will not hurt the engine or emissions system in any way. It's designed to recognize the difference in octane and make the appropriate adjustments. Keep in mind that rated HP and torque (172 hp @ 6,000 rpm, 162 lb.-ft. torque @ 5,000) is only fully available when using 91 octane. Should you chose to run 87, you'll be down a few ponies and a little bit of torque. Many people don't notice a difference between premium or regular. Same for mileage.

My experience has been that I get slightly better mileage, and more "umph" at freeway speeds with premium than regular. Cost is a wash. I save somewhere between zero and $100 a year using premium. So its a no brainer, I use premium.

Don't listen to me though. You really need to try it yourself. Run premium for a month and record the cost and mileage, then run regular for a month and compare the numbers.

 

IMO.....

Doc Brown provides the best COMMON SENSE advise related to this topic

But a slight correction to the OP, bigjoe......

I believe if you read your Owners Manual it states PREMIUM preferred....not 91 octane. I'm only relating this because I have been in some "boonies" parts of our country that only have 89 as a "premium" (as well as areas that have 94). GM had taken this in to consideration when designing this engine and writing the specs.

Also bigjoe....do a search related to your topic. You'll discover many threads related to the subject which may provide additional info for you to make a decision.

 

I've been running 87 octane for the most part in my 06 LT1 w 2.4L engine. I've been averaging a tad over 30 mpg. I tried running 93 octane for 2500 miles and saw no mpg improvement. It felt as though there was more performance improvement, but I don't drive the HHR for performance. Not worth the extra $0.25/gallon for premium.

 

Thanks everyone for the advice. Had to re-read the owners manual and it does read to use premium unleaded gasoline with the posted octane of 91, however regular unleaded rated 87 or higher can be used but your vehicle acceleration may be slightly reduce...

I will stick with 87 since its doing fine and has good acceleration.

 

I split the difference and use the mid grade 89 octane. No performance problems to speak of in the 45 days I've owned my HHR. I only have about 675 miles now with 300 coming from a single trip. I did notice some sluggishness climbing hills compared to my previous vehicle.

Fred

 

Honestly... the engine is just going to pull timing so there is no knock. You are gonna lose 10hp or so. If you'd rather keep the extra few dollars in your wallet at fillup stick with regular... but I'd rather have the performance, I'll run premium from this point forward.