Topic: What Does “Premium Fuel Recommended” Mean?

[dkaz]

Regular gas is dirtier than premium? You’ve bought the Kool aid.

Not the fuel itself.  But if the car calls for premium and you run regular, the car pulls timing and you might have a less complete burn...which could mean more deposits left in the combustion chamber.  Plus it might run hotter, shorten the life of the spark plug...which also further could result in less efficient burn and deposits.  But that's not terribly likely these days...unless you're turbo or towing a load.

But in an of itself...you're right.  Both regular and premium contain detergents and neither is "dirtier" than the other.

I would say most Sienna, Highlander, Camry V6, and Avalons have never seen a lick of premium fuel in its entire life and a lot of the older ones are reaching 400,000 km no problem.

[rrocket]

^^Shrugs.  I don't care.  If the owners are cheapskates, that's their business.

I have seen engines that have run regualr and others premium after long term..and I will say the premium engines were cleaner on the cylinder head and piston tops. 

But yea..shouldn't affect longevity...once again...UNLESS you are regularly towing are putting excessive load on the engine in which case you NEED the premium...since the computer can't pull enough timing.

[JG20]

And the ECU pulling the timing means knock is happening in the first place. Personally, I don't want knock to happen at all, or at least minimize it.

[ChaosphereIX]

yep that is what I meant - if an engine can run 87 and 91, when it runs 87 it will be pulling timing, which needs knock to happen for it to do that in the first place, and runs the risk of incomplete burn. Over the long term, could mean something...maybe not. Pulling timing etc. just to me seems like the engine is "compromising" and deliberately making itself worse. Why not run an engine at its optimum level?

However, regardless as rrocket says...the discussion is ended if the engine is towing or under any forced induction. We are not talking about lazy V6s in a Camry, but turbo, supercharged and high stress engines. My JCW calls for 94 "recommended" with its high flow head tune...and it CAN run 91 but it is pulling timing etc. to get there...so emergencies only and no WOT at all IMO. 94 is what it was tuned for, so it gets 94.

[tortoise]

my tank is only 43L, so it's usually only about $35 to fill, with the extra cost of premium likely only about $4/fill...co regular.

In Ottawa it's a 20 cent differential. So that's $8.60 more per tank.

$13 more for the Highlander. that.

[ArticSteve]

Hot climates like Texas in the summer, mountain elevations or maximum loads then 91.  Of course if it's a lease then 87 all year long. 

[rrocket]

my tank is only 43L, so it's usually only about $35 to fill, with the extra cost of premium likely only about $4/fill...co regular.

In Ottawa it's a 20 cent differential. So that's $8.60 more per tank.

$13 more for the Highlander. that.


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It's 12 cents at Costco...I just looked.

[ArticSteve]

be a hell of a lot more in a few months 

[rrocket]

be a hell of a lot more in a few months 

a 60 cent dollar has a way of doing that I think....

[ArticSteve]

talking about the carbon tax in April.  That will have some major blow back because of the US start to summer.

[johngenx]

Regular gas is dirtier than premium? You’ve bought the Kool aid.

Not the fuel itself.  But if the car calls for premium and you run regular, the car pulls timing and you might have a less complete burn...which could mean more deposits left in the combustion chamber.  Plus it might run hotter, shorten the life of the spark plug...which also further could result in less efficient burn and deposits.  But that's not terribly likely these days...unless you're turbo or towing a load.

But in an of itself...you're right.  Both regular and premium contain detergents and neither is "dirtier" than the other.

I would say most Sienna, Highlander, Camry V6, and Avalons have never seen a lick of premium fuel in its entire life and a lot of the older ones are reaching 400,000 km no problem.

This.  Lots of 3MZ-FE engines out there with very high mileage that haven't had a drop of anything other than 87 octane in them and  they're fine.  The engine was designed to run reliably on regular fuel as it simply advances the timing to the point of whatever octane you're running.  I ran a few tanks of premium, made no difference to feel or fuel economy.

This idea that 91 octane is "better" than 87 is a myth.  It's just more resistant to detonation.  Octane is not BTU.  A liter of gasoline contains about 32,000 BTUs, regardless of octane rating.  The performance of your engine, including economy, is dependent on a large number of variables.  Even advancing the timing might not result in any gains thanks to combustion chamber shape, valve timing, cam profiles, and on and on.

I like to treat my cars right.  I use premium synthetic oil, top tier oil filters, quality parts and so on.  But, in a lot of cases, the 20% premium for premium is wasted money.  If your manual calls for premium, use it.

[rrocket]

This idea that 91 octane is "better" than 87 is a myth.

Is certainly isn't a "myth".

Put a turbo car under boost or a vehicle towing a heavy load. 

87 will knock, pull timing.

91+ will allow full power with no (or minimal) knock.

So one is certainly "better".

94 vs 91 was worth 6+ pounds of boost in my Supra....are you going to tell me the higher octane fuel wasn't "better"??

There's like a million dyno charts online where people have dynoed cars for fun on 87 vs 91 octane....one is clearly better than the other (in certain applications).


BTW...how'd your beastly Busa run on 87 octane?   

[bridgecity]

“In certain applications”. 

Ya, no kidding. My Tundra certainly never knocks with 8000 lbs in tow with 87 octane. 

[dirtyjeffer]

my tank is only 43L, so it's usually only about $35 to fill, with the extra cost of premium likely only about $4/fill...co regular.

In Ottawa it's a 20 cent differential. So that's $8.60 more per tank.

$13 more for the Highlander. that.

Costco...it's 12-14 cents/liter...plus, i have the Costco Mastercard, so i get 2% cashback on all gas.

[rrocket]

“In certain applications”. 

Ya, no kidding. My Tundra certainly never knocks with 8000 lbs in tow with 87 octane.

It probably does...you just can't hear it.  The accoustic knock sensors re-act quickly, so it's hard to tell.  If you can hear it bad....that's REALLY bad!!   

If you have TorquePro, you can use a knock sensor and visually see it....

Also...Tundras are pig rich from the factory.  AFRs in the 10s IIRC....so that likely helps.  I know with just a simple tune, guys were picking at 20HP/20TQ...pretty bananas for a stock, NA, truck...

[dkaz]

In BC and Alberta, premium at Costco is typically 10 cents higher than regular. I’ve seen 12 on the odd occasion.

[rrocket]

In BC and Alberta, premium at Costco is typically 10 cents higher than regular. I’ve seen 12 on the odd occasion.

Good price!!

[tortoise]

It's 12 cents at Costco...I just looked.

Ain't nobody got time for that.

The nearest Costco to me isn't that convenient and the line up is always absurd. I think I've filled up there 3 times in the last 4 years.

[mlin32]

I like how in Europe my only choices for gasoline are both considered "premium" in North America : 95 or 98 RON (90-93 AKI for you guys in Canada)  . You can get "Race 102" at some Shell and BP stations in Germany, but uh, why ?

Yes, I have a turbocharged motor. 1,6 litres putting out max. 205ch . And unless I'm feeling spendy and driving in the mountains, I just fill with the cheaper 95  .

Back in the US, I did the same always with my cars too : the equivalent of 90-93 AKI . So I'm consistent. Fuel is cheap in North America so although I gripe about the price differential, I often swallowed it.

[greengs]

So here is an actual video of a guy who did some research including dyno runs.  Running premium makes negligible/no difference in all the vehicles they tested, he tested timing and power.   

Tested:
F150 3.5EB
Escalade 6.2L V8
MX-5
Audi A3 1.8T
Mustang 5.0L
Renegade 1.4T

https://www.youtube.com/watch?v=dxAQmj3P8xs