Gasoline thread

[phil-saab]

Warning: information below may upset our European Saab friends where petrol costs an arm, a leg or possibly both...!

I was surprised to see the drop in gas price in the last few weeks. Looks like it has been the lowest in four years.

Lowest August gas prices in four years - Aug. 1, 2014

Diesel is still more expensive than premium, one of the reasons diesel cars will probably never be a huge success in the US.



Regular is about EUR 0,66 per liter or CAD 0.92 per liter.
Premium (Super +) about EUR 0,72.

I'm still very envious of your petrol prices fella, I always fill up with Shell V Power, reason being is my 9-5 Aero is now at Stage III tune, also, here in the UK V Power is 98 octane! Some of the guys with serious performance even mix paint thinners in the tank with the petrol! At the end of the day I think the US emmissions are possibly more strict than ours.

[Dave T]

I recently rented a Hyundai Sonata and looked at the owner's manual. Among their maintenance requirements is to use Hyundai fuel cleaner with Techron every 7,500 miles unless Top Tier gas is used. That leads one to believe that Top Tier Gas standards might actually be better.

A few months ago, I read an AAA article about Top Tier gas.
http://newsroom.aaa.com/2016/07/aaa-...created-equal/

ORLANDO, Fla. (July 7, 2016) – New testing from AAA has uncovered significant differences in the quality of gasoline sold at fuel retailers in the United States. The independent laboratory testing compared gasolines that meet TOP TIER™ standards often marketed to consumers as having enhanced, engine-cleaning detergent additives with gasoline brands that do not participate in the automaker-backed program. Among brands tested, non-TOP TIER gasolines caused 19 times more engine deposits than TOP TIER brands after just 4,000 miles of simulated driving. Such carbon deposits are known to reduce fuel economy, increase emissions and negatively impact vehicle performance, particularly on newer vehicles. To protect vehicle investments, AAA urges drivers to use a gasoline that meets TOP TIER standards for engine cleanliness and performance.

An old post in this thread is also informative.

Tesoro, which retails gasoline through 800 of its stations and distributes fuel to Wal-Mart and others, views the detergent issue as a gimmick. Tesoro doesn't put in additional additives because "our customers are price shoppers," says Senior Vice President Lynn Westfall.

"People will switch for a penny. It might not make financial sense, but they'll do it," says Jeff Lenard, spokesman for the National Association of Convenience Stores

http://usatoday30.usatoday.com/money...wsf010ygl014ak

However, so many brands are now Top Tier listed that it is easy to buy without paying too much more. If one is economical, one might even add about 1 oz. of Techron per tank of non-Top Tier gas.

[southsaab]

After switching to a top tier gas(Shell), I had improved MPG, up to 31MPG on a recent trip. And mine is an automatic. Interestingly, I refilled with Exxon, and seemed to have a bit better mileage, but I can't swear to it. Car had one more person with luggage than the previous trip.

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[xorlando]

Hopefully I am no necro-posting here to ask - what is the preferred or optimal octane for gas in a Saab?
Specifically a 2005 9-5 wagon in Linear trim, manual transmission.

Since I bought it a year and a half ago, I've always put in "premium" bc I'm pretentious . My bf however has said that some cars run better on lower octane, or at least don't see performance increases over a specific octane.

All I've found in the forums so far is to go for 87 or higher, which seems like a low bar.

Any published specs available?

[southsaab]

Saabs prefer premium. Regular is usable, but performance does suffer. Trionic adapts to whatever octane is used. But there is much debate about this. I read on an Acura TL site the best comment concerning high performance engines and octane: "why would you buy a premium car, expecting its best performance, and use premium fuel?" I don't know about you, but I couldn't come up with a good answer...

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[Dave T]

My bf however has said that some cars run better on lower octane, or at least don't see performance increases over a specific octane.


Any published specs available?

It is true that there is an optimal octane and some octane levels are higher than that. For example, if you found 94, I don't know if that's any better.

I don't know the exact optimal octane but the US EPA rated the 2005 Saab 9-3 as 1 mpg higher highway mileage with premium. I also did a year long test and confirmed that there is slightly better gas mileage with 93 octane but that the savings from better gas mileage did not cover the higher cost of premium.

The 2005 9-3 recommended 90 octane, which is a bit higher than midgrade in the US, which is almost always 89.

In areas that sell 87, 89, and 93, the price of 89 is often exactly in between 87 and 93, which doesn't seem like a good value to me. Some people estimate the amount of gas needed and pump half premium then half regular to yield 90 octane. I never alternated a tank of premium with a tank of regular because I didn't want the engine to sense different octane by knocking and readjust. Instead, I kept the octane the same except during the year long test, then only gradually changed it. I did see a linear change, i.e. estimated 92 octane gave better mileage than 90. I didn't go lower than 89.6 or so.

In the winter, the needed octane is lower. With my 2005 9-3, my goal was 90 octane in the winter, 90.8 octane in the summer.