Regular vs Premium

<div class='quotetop'>QUOTE(bulldog @ Jul 27 2006, 04:30 PM) [snapback]293380[/snapback]</div>

Lower octane actually has more energy in it. Put the lowest number you can in your Prius and you'll be a happy camper. In Utah I have the option of feeding it 85, and it works great. In California, is 89 the lowest option? If so, just take the lowest regardless.

 

I agree, when I am in one of the high altitude states such as Utah or Colorado I use 85. When I am in Oregon or Washington I use 87. No reason to go higher than that unless you can't get anything else. BTW I think the owners manual says 87.

 

The Prius is designed to sip lower octane fuel (85 or 87 depending on what is available where you are). Putting premium in instead doesn't do anything but drain your wallet of any extra $ that could otherwise be better spent elsewhere.

 

premium fuel can cause starting problems.

 

I think that regularly putting high octane gasline into a car that's not designed for that kind of fuel can, over time, damage the emissions system.

 

Hi Bulldog,

How old is your 4R, and have you used it in allot of stop and go driving in warm weather? I ask this because its common for engines to kinda grow into needing the higher octane, as the compression ratio increases due to the carbon deposits. If the car is knocking on regular, it will get better mileage on higher octane.

 

Crap...I've always been more keen to using the higher octane no matter what the car. Will the 93 (here inn Florida) really damage the engine? I always had the belief that the higher octane will improve gas mileage, engine burn, etc. Doesn't the manual say 87 or higher?

 

<div class='quotetop'>QUOTE(tyrael @ Jul 27 2006, 07:34 PM) [snapback]293600[/snapback]</div>

Our FAQ page on it. Higher octane is useless and possibly detrimental if the engine isn't designed for it.

 

<div class='quotetop'>QUOTE(tyrael @ Jul 28 2006, 12:34 PM) [snapback]293600[/snapback]</div>

No, I doubt 93 will damage the engine. If it did, I would see alot of lawsuits coming the gas companys way.

In fact, I believe higher octane is good for the engine, and has a cleaner engine burn.

BUT, it won't improve gas mileage, unless something in the engine is causing it to have poor mileage on the regular stuff (like carbon build-up, or simply because the engine was designed to run on the higher octane only).

Jimmy

 

<div class='quotetop'>QUOTE(jimmyhua @ Aug 2 2006, 10:38 AM) [snapback]296252[/snapback]</div>

This is not true, exept in cases where the engine is designed specifically to burn higher octane fuel. The Prius's ICE wasn't designed that way, so just stick to 85/87.

 

I've found it helpful to temporarily burn premium fuel in older cars that had carbon deposits, until I could get the car serviced. The carbon deposits contributed to knocking, and higher octane fuel reduced the knocking (apparently the ECU was not one that detects knock and retards the ignition). But this was only a temporary measure for a vehicle requiring service, not something you should do on a vehicle with a properly running engine.

 

<div class='quotetop'>QUOTE(priusenvy @ Aug 2 2006, 10:23 AM) [snapback]296391[/snapback]</div>

Are you sure it wasn't the higher-level of detergents in the "premium" fuel you used?

I have the impression that Chevron uses the same amount of detergent in all their grades, and so is my preferred fuel. Tried Chevron regular to see if that reduces your knocking the same?

<div class='quotetop'>QUOTE(jimmyhua @ Aug 2 2006, 07:38 AM) [snapback]296252[/snapback]</div>

Even if the FTC, gas companies, Toyota engineers, and people here say the opposite as in the previous FAQ link?

 

<div class='quotetop'>QUOTE(NuShrike @ Aug 2 2006, 01:32 PM) [snapback]296517[/snapback]</div>

Yes, I'm sure it wasn't the additional detergents. The reduced pinging is observed immediately. Any cleaning of the combustion chambers would take several tanks - and on the few occasions where I've had to do this, I was dumping in a bottle of Techron (the strong version) at the same time I was refueling. That has much more cleaning effect than the detergent additives in gas. The detergent levels in gasoline are more to prevent deposits, rather than to eliminate existing deposits.

Once Chevron started advertising that they put the same amount of detergents in regular as premium, I started buying my regular gas at Chevron. Before that I would just buy gas at Costco and resign myself to getting the throttle bodies and fuel injectors on my cars cleaned every few years (and they needed it).

 

My Prius has a belly full of straight 87 (the dealer paid for me to fill it from flashing pip to full, and I've refilled once, both 87). I can not get mine to ping at all. Not even a hint of it. This car is a well-kept 2004 with only 15k miles.

IMO, there is endless confusion on this subject because some mainstream cars (a minority) are designed to run on either regular or premium. The Avalon, Camry V-6, and ES350 are great examples from the Toyota stable. They've all got the same basic 2GR-FE V-6. Its knock sensors and ECU are designed so that if you feed the car premium, it will advance ignition timing substantially, resulting in a moderate max output gain. If you feed it regular, the ECU will "hear" the feedback from the knock sensors, and retard spark timing to suppress the onset of ping and/or knock (also resulting in a loss of performance). In the owner's manuals for such vehicles, you'll see language to the effect of, "87 octane fuel is acceptable, but 91 or above is recommended for increased performance". A couple years back, Toyota got busted by the gov't for advertising the premium fuel hp figures, while allowing the use of 87 fuel. Now they have to advertise the hp/tq figures generated on the lowest allowed fuel. Notice now how for the ES350, Lexus advertises higher output figures that Toyota does for the Camry or Avalon (272 hp for the ES, 268 for the Camry). Lex "requires" premium for the ES, whereas Toyota does not for the Cam/Av. The disparity was much greater for the last gen Camry and its 1MZ-FE V-6, which "dropped" from an advertised 220 hp to 192 hp so that Toyota would not have to "require" the use of premium in its mainstream Camry. The VQ35DE in my G35 was the same; Infiniti just dictates premium now so they can advertise 298 hp (vs. the 260 or 280 seen in earlier versions).

Anyway, none of this applies to the Prius, which obviously, is not balanced in favor of maximizing hp and torque, at least not at the expense of fuel economy. The manual says "87 or higher", and the "91 or above is recommended for increased performance" language is notably absent. There's really no benefit to be gained using mid or premium gas in this car, unless you've got a ping or knock problem, in which case, you'd better be headed to the service dept for some diagnostics.

EDITed for typo.