I use 91 in Denver and 93 where available. I have tested 91 in my son's LS MT and there is a definite improvement in drivability, low end power, and fuel economy.
And it begins again...Unless specifically called out for your car, don't waste your money on higher octane fuel. Octane is merely a measure of a fuel's resistance to autoignite (i.e. knock). It has nothing whatsoever to do with the energy content and will not provide more MPG in and by itself.
You mean the one showing the RPO code for 91 octane.The funny part is the post is just below my post.
Yes, I read your post. However, unless you understand how the Cruze's ECU manages the fuel ignition there is no way to understand why the Cruze can safely run on 87 octane despite the engine being designed for and carries the RPO code for 91 octane. There are two ways to reduce/prevent knock (premature fuel detonation) - one is to run higher octane - the other is to change the timing of the spark in the cylinders to prevent excess fuel from accumulating. GM's engineers appear to have detuned our engines in addition to adding serious knock sensors to give the ECU immediate feedback so it can protect the engine from too low of octane.Thanks for the replies, guys. But, did you read my post? After getting this rep statement, I think not:
"You have no idea what you are talking about. In this application, it makes a difference. Do your research before you post."
My post said absolutely nothing about ignition timing. If 91 RON indeed does produce better MPG than 87 RON, then certainly ignition timing might explain it. But, please read my post again before whoever you are send me such nonsense rep lines. And, as background, I started as a mechanical engineer working for Ethyl Corp (experts in spark knock) at their research facility in Ferndale, Michigan, and there is no power to be had from octane in and by itself. Ethyl's R&D facility is long gone now, but octane still by itself does not produce more power.
First, that article is 10 years old. Second, it really highlights the differences in customer service in the US vs. Canada, one that we still see today with Chevy Dealerships.So you are saying 89 doesn't even make the grade? I found 91 overkill and at 40 cents a gallon extra. 89 is 20 cents extra and works just fine? Perhaps the key is to have a new engine like mine with 3K before the system gets gunked up, like every computer I have owned? I don't trust Shell after what they did to Florida and Canada about 10 years ago. Interesting GM twist too?
Toronto Star: Shell shells out for tainted gas: Canadians denied help for problem
TONY VAN ALPHEN
Jun. 4, 2004.
Sulphur harms gas gauges in Florida
Oil giant Shell is reimbursing motorists in Florida for fuel gauge repairs made necessary by contaminated gasoline, something its Canadian subsidiary wouldn’t do here last year.
An official for Shell Oil’s refiner in the United States has confirmed it will start sending cheques today to customers who complained about faulty gauges after buying gas containing corrosive elemental sulphur from the company and Texaco.
Johan Zaayman, a spokesperson for refiner Motiva Enterprises, said yesterday Shell has received more than 9,000 claims for the cost of repairs in less than a week from customers in Florida and nearby states after the company acknowledged a problem.
“We’re accepting claims from customers to get reimbursed for the cost of the repairs of the gas gauges,” Zaayman said in a telephone interview from Motiva’s offices in Houston.
“The cheques will begin to go out tomorrow (Friday),” Zaayman said.
In the last week, hundreds of Shell, Chevron and Texaco service stations have sold gas with traces of elemental sulphur, which quickly corrodes the contacts on sending units in tanks and, in turn, triggers faulty gauge readings.
Motorists have run out of gas and stalled when fuel gauges read full but tanks were actually empty.
Like Shell, Chevron says it has set up a special customer hotline and will cover the cost of repairs. Costs could range from $300 to $600 (U.S.), dealers say.
The reaction by Shell in the United States differs from how the company handled customers in the Toronto region last spring and summer.
A Shell official in Canada said yesterday the company handled customers appropriately here by sending them to their dealers for reimbursement of expenses.
“When we learned of the problem, we co-operated with our mutual partners (the auto industry) to understand it,” said Simone Marler, manager of public affairs for Shell Canada Products.
“We then added an ingredient to our gasoline. We directed our customers to their dealers for assistance. Our goal was to make sure our mutual customers were looked after. And they were. The issue has been resolved.”
Marler said she was unaware of the circumstances in the U.S. incident.
Unsuspecting motorists bought gas tainted with elemental sulphur at Toronto-area Shell and Petro-Canada service stations in the spring and summer of 2003. They got inaccurate gauge readings and stalling, a safety hazard on busy roads.
After a lengthy investigation, Shell and Petro-Canada concluded months later their gas contained elemental sulphur.
The two oil companies denied responsibility for the faulty fuel gauges. They stressed their products exceeded industry and government standards.
At one point, a Petro-Canada official said General Motors was responsible because it used an inferior part, but later the oil company said it wasn’t sure what the problem was.
Shell sent customers back to their dealers, primarily GM, for reimbursement of repairs. But many customers expressed dissatisfaction with their treatment by dealers and GM’s refusal to pay for repairs.
A Star investigation showed that GM had encountered the problem in 2000 in parts of Canada and the United States.
GM sent a notice to customers warning them about the problem and corrective action but it did not issue a recall.
It redesigned the fuel sensors so they could tolerate elemental sulphur. However, the company only started using the new sensors in models last year. GM confirmed it accelerated the installation of the redesigned part in more models late last year.
The investigation found GM notified dealers on how to handle customers in last year’s incident, but the company never warned customers.
Earlier this year, GM offered a free oil change and a Petro-Canada cash card worth a total of about $55 to customers who had gauge problems.
In Tampa yesterday, Skip Greaney, fixed operations manager at Gordon Chevrolet, said the number of repairs of fuel gauges in his shop shot up to 42 in May and 10 to 12 in the first two days of this month. There were only nine similar repairs in the first four months of the year, he added. “There’s been a huge spike,” he said.
Meanwhile, two women from Fort Lauderdale, Fla., who say the sulphur in the gasoline damaged their cars, have filed a lawsuit against Shell Oil Co. and Motiva, alleging the companies violated state law by engaging in unfair and deceptive trade practices. Shell owns half of Motiva.
The lawsuit says the companies “knew or reasonably should have known” that the gasoline with the sulphur would have damaged the vehicles but they continued selling the fuel to motorists.
My recommendation to everyone is as follows:So you are saying 89 doesn't even make the grade? I found 91 overkill and at 40 cents a gallon extra. 89 is 20 cents extra and works just fine?