Octane grade for Subarus

Some do, some don't. My 2000 Forester 169k miles gets by on regular. I had a 1985 4WD Turbo that needed premium and 20W50 oil! My 1992 Loyale needed premium when it got old around 150k miles and after.

I wonder what octane ratings are specified in the Owner's Manual of the latest Legacy and Impreza models (2010 & 2011.)

Depends on the model. Legacy here:

Remember the old days when one could just retard the timing a bit to get rid of engine ping? A timing light and a wrench to loosen the distributor were standard tools. So was a matchbook to set the point and spark plug gap.

Thanks for the link. That's cool. The Legacy 2.5i and the 3.6R both require regular 87 while the 2.5 GT requires premium 93. I want one. Maybe a 3.6R.

Thanks indeed! I wonder where GT owners find 93 octane gas though. The 3 grades I see around are 87, 89 and 91 octane.

I wouldn't want to date myself that far back. ;-)

Seems like that's the only date I can be sure of anymore and they sometimes don't work out so well either.

You got me looking in the bottom of my garage tool box. Wonder what a timing light and dwell/tach meter are good for these days? I've also got the old gauge for setting plug gaps which is still good for my garden equipment.

Thanks indeed! I wonder where GT owners find 93 octane gas though. The 3 grades I see around are 87, 89 and 91 octane.

The difference between US and UK fuels' octane rating is interesting. Our standard supermarket low octane petrol is rated at 95 octane. We also have 99 octane fuel (+5% bio fuel) easily available which I run my WRX on and yes, it does make a difference. Most noticeable is much smoother running and acceleration from low revs. An overall better performance, lower consumption and no residue build-up is claimed. On one of the rare occasions I monitored fuel consumption on a long run I averaged 34 mpg which surprised the hell out of me!!

-C- Anything is possible if you don't know what you're talking about

I've set a few that way...

My 2003 H6 3 liter outback runs best on 93, if you dump in 87 it detects the ping and retards the timing.

Dave

Same here. Indeed some folks say they've done the math both ways and the decreased mileage when running low octane fuel defeats any cost savings. Thayt may not be true for all cars or driving styles.

The majority of cars that "require" premium fuel do just fine without it. Are people so gullible to think their car won't run on regular fuel? What if there was none available in the sticks? Use regular and save a lot a money!

That's fine with newer cars that automatically adjust the timing with lower octane fuel. Older cars using below spec fuels can damage the engine with knocking etc. They will run, but won't be good for the engine.

Yes, most engines equipped with knock sensors or otherwise adjusted for lower octane will safely run.

But, there are multiple sources of information about tests that definitively show a DECREASE in fuel efficiency when cars DESIGNED to utilize high octane fuel are operated with low octane fuel. Autohaus,wikipedia, Lexus ,edmunds, CNN, etc. basically, retarding the timing on ANY car will reduce fuel efficiency. And this is how a vehicle designed for high octane must deal with lower octane to avoid potential damage from knock - by retarding the timing.

HOWEVER, if your car is designed for low octane(and has no modifications or problems) - there is absolutely NO advantage to running high octane fuel.

Check your manual. Trust me, Subaru engineers would LOVE to tell you your car is designed for low octane, they'd get fewer complaints about the expense of operating the car. But high compression engines are less efficient on low octane than the high octane they are designed to use. You will also enjoy better responsiveness/power using what your manual suggests.

My 2008 STi will not run well on regular fuel. The book says 93 octane and allows for 91 if you have to, but warns of poor performance. I've tried both. Mileage and performance are MUCH better with the 93. The car isn't really supposed to be an economical vehicle to drive, but what are you going to do if you want the kind of punch and power a turbo-charged 340 whp torque monster can deliver. I LOVE this car! David

Cool. I love my 06 WRX wagon. It's plenty fast enough for an old guy and it's DL so no problems from cops, kids wanting to race etc. I ALMOST got an STi but really didn't need the higher insurance. Plus, i wanted a wagon.

I read where Toyota's 'Lexus College' in Japan tested one of their vehicles and it dropped 6mpg switching from the recommended high octane to low.

Where do you find 93 octane gas? Here in the Puget Sound area the highest octane gas I find is 92.

I think Amoco used to have 93, but I haven't seen one of them around here in ;a long time (south central PA).