new car

stawk

so i just got a new car. A subaru legacy gt, she has a turbo and all the goodies and what i was wondering is that i was told it required premium and is it ok to put midgrade in or even regualr considering she eats gas like pac man eats dots and it is getting really expensive to put in 40 bucks a week into her...

RUNN1NGMAN

stawk wrote: »

so i just got a new car. A subaru legacy gt, she has a turbo and all the goodies and what i was wondering is that i was told it required premium and is it ok to put midgrade in or even regualr considering she eats gas like pac man eats dots and it is getting really expensive to put in 40 bucks a week into her...

Well... usually it's not a big deal because modern cars can detect the grade of the fuel you use and adjust performance accordingly. However, you bought a car with a high-performance engine, and it needs premium to run it's best. If you use a lower grade of gasoline performance and fuel efficiency will suffer (so you may not end up actually saving any money). Buying premium gas is the cost of having a performance car.

One thing to check is whether your manual or the gas door sticker says "Premium recommended" or "premium required." If it's the latter you can actually damage your engine by using low grade. There are very few "premium required" cars though, because most cars can electronically adjust the timing to compensate for the ignition point of different grades of fuel.

milehigh

First off, congrats, and great choice! I'll promote these cars until they day that I die. I absolutely love mine (have a 2005 limited). I do fill it with premium though, there's arguments for or against, but honestly I'd rather play it safe and go with what's going to give optimal performance and (hopefully) keep the engine in better shape for the long term.

Also just an FYI on a good resource for all things LGT: http://www.legacygt.com/ Lots of good forumers and these people have done (or tried to do) just about everything you can imagine and then documented it in great detail.

eternalbl

Check the owners manual for the minimum recommended grade of fuel and stick to that. You wouldn't want to have warranty work declined on a technicality so you can save a couple bucks a month.

BronzeDuck

You maybe *could* but why risk it? As runn1ngman said, even if the car retards the timing, you'll likely end up with worse gas mileage negating any savings you may achieve. Also have the potential to hurt the car during um, more "spirited" driving sessions, if you're into that kind of thing.

Also, if it's cold out where you are, that will significantly reduce gas mileage. I have an 05 WRX that'll get me 23-24 around town in summer, in winter I'm lucky if I get 18-19.

tribenet

Turbo'd cars usually require higher octane because of the engine compression involved.

You MAY use 87 octane, and the ECU MAY retard the timing. But you have ask yourself.. why is it pulling timing? Well.. usually because a engine knock sensor triggered it. Engine knock == bad.

If the ECU retards the timing, the knock already happened at least once. BLEH!



EDIT: Err.. realised this may not be quite clear. The point of octane is to augment the fuel's "compressability". Engine knock is the condition where the fuel ignites before the spark plug actually does it. In this case, bad things can happen.

travathian

Why'd you spring for a turbo if you're going to get chintzy on the gas?

Also, learning how to go easy on the gas pedal can save you lots in fuel costs.

Midshipman

Please do not put anything less than premium into a turbocharged car. Like Travathian already mentioned, learn how to accelerate gently and also learn to plan your deceleration to avoid braking as hard or frequently.

Djeet

I've put about 45K miles on my Legacy GT and do most of the maintenance myself. I regularly use 87 and haven't noticed any ill effects (e.g. no engine codes thrown, no issue with emissions, not wearing oil any faster). The change in performance when you drop the hammer is there, but it's still fun to drive.

One thing I'd say about the 2.5L turbos on subies is you really need to change the oil every 3K, every 3500 absolute max. At least in the Texas heat, the oil is totally black at 3750 (yes, I use synth).

RUNN1NGMAN

Djeet wrote: »

I've put about 45K miles on my Legacy GT and do most of the maintenance myself. I regularly use 87 and haven't noticed any ill effects (e.g. no engine codes thrown, no issue with emissions, not wearing oil any faster). The change in performance when you drop the hammer is there, but it's still fun to drive.

One thing I'd say about the 2.5L turbos on subies is you really need to change the oil every 3K, every 3500 absolute max. At least in the Texas heat, the oil is totally black at 3750 (yes, I use synth).

FYI, color is not a good indication at all of whether your oil needs to be changed. Modern oil has detergents in it that clean gunk and stuff from your engine parts, so its supposed to turn black and rather quickly.

Djeet

Color's not perfect, but it's good enough. The oil will likely turn darker before its shorn enough to change viscosity, but when it's black it's probably past time to change. I usually do "feel" the oil (make the "gimme cash" sign with some spent oil between thumb and 1st 2 fingers, you can usually get enough off of your dipstick) and by the time it's black it's done.

I hadn't heard about the detergent thing and cleaning gunk off the engine discoloring oil; I'm not sure what to make of that. I will say that protracted length of time between oil changes on subie forced induction engines was considered one of the culprits in high head gasket failure rate.

I've also seen oil drained from a Porsche after 15K miles, still honey-colored and "feeling" unused.