Suzam Posted July 30, 2007 Share Posted July 30, 2007 I'm considering looking at a MY96 2.5 LSi wagon. I know that was the year for preminum fuel, but is it really needed? I'm looking to replace our wrecked MY 95 L 2.2 for my daughter and I know she won't want to pony up the $$$ for preminum, let alone remember to buy it and not regular grade. Quote Link to comment Share on other sites More sharing options...
Reveeen Posted July 30, 2007 Share Posted July 30, 2007 I know that was the year for preminum fuel I *really* have trouble with this. Subaru recommends premium fuel period (in all cars since 1990), why would you, or anyone else, have trouble with this? Here is what is going to happen: Knock sensor detects knocking, timing auto-retards, gas mileage drops 3-10mpg (depending on your driving habits), savings 0 (none), in fact it will cost you "real" money every visit to the gas station. Help me out please, because I really don't understand? Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 30, 2007 Author Share Posted July 30, 2007 Help me out please, because I really don't understand? That's kind of why I'm asking too. Quote Link to comment Share on other sites More sharing options...
uniberp Posted July 30, 2007 Share Posted July 30, 2007 Subaru recommends premium fuel period ?? where is this recommendation? Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 30, 2007 Author Share Posted July 30, 2007 I think it was in the owners manual and http://www.cars101.com/outback_archive95-97.html#1996%20Outback There was a change in the heads, I belive, for that year which increased the compression. Then it was revised again for the next year's 2.5 Again, it was a "recommendation" from SOA. So I really wonder what, if any, issues would occur if regular was used. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted July 30, 2007 Share Posted July 30, 2007 Premium is recommended for certain engines, but not for all. The manual will state whether regular can be used when premium is recommended. Like it may say "Premium unleaded gasoline (91 octane) recommended*** Regular unleaded gasoline with an octane rating of 87 AKI or greater may be used. Using regular unleaded gasoline could result in reduced engine performance. See Owner's Manual for more detailed information." Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 30, 2007 Share Posted July 30, 2007 I think it was in the owners manual and http://www.cars101.com/outback_archive95-97.html#1996%20Outback There was a change in the heads, I belive, for that year which increased the compression. Then it was revised again for the next year's 2.5 Again, it was a "recommendation" from SOA. So I really wonder what, if any, issues would occur if regular was used. 96 OBW w/DOHC 2.5 phase 1 engine. Owner's manual recommends 91 Octane, but 87 can be used. In the almost 12 years and 222K miles on this car I have tried all types of octane and brand fuels. It basically runs fine on 87, the octane I used in the majority of it's life. It may ping once in awhile under load (going up a hill, fully loaded, etc). 91 Octane takes care of that, and we have several stations here the sell all the mid-grade and premium fuels for the same prices as regular. The happy medium for me lately, and the OBW, is mid-grade, 89 or 90 octane. But no big issues in using 87, at least not so far. BTW, gas mileage seems unaffected between the different octanes, at least any measurable differences by standard observations. Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 30, 2007 Author Share Posted July 30, 2007 96 OBW w/DOHC 2.5 phase 1 engine. Owner's manual recommends 91 Octane, but 87 can be used. In the almost 12 years and 222K miles on this car I have tried all types of octane and brand fuels. It basically runs fine on 87, the octane I used in the majority of it's life. It may ping once in awhile under load (going up a hill, fully loaded, etc). 91 Octane takes care of that, and we have several stations here the sell all the mid-grade and premium fuels for the same prices as regular. The happy medium for me lately, and the OBW, is mid-grade, 89 or 90 octane. But no big issues in using 87, at least not so far. BTW, gas mileage seems unaffected between the different octanes, at least any measurable differences by standard observations. That's the kind of info I'm looking for, I figured as much. Our MY01 Outback knocks occasionally on the recomended regular octane. If anyone else has some real time experience with this engine and regular fuel I'd like to hear about it before I go looking at the car. Thanks! Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 30, 2007 Share Posted July 30, 2007 That's the kind of info I'm looking for, I figured as much. Our MY01 Outback knocks occasionally on the recomended regular octane. If anyone else has some real time experience with this engine and regular fuel I'd like to hear about it before I go looking at the car. Thanks! Remember to ask if the head gaskets have ever been replaced. While I like this engine, it has bitten quite a few people, myself included, in the pocketbook for HG replacement. Just don't want you to have expectations of saving nickles and dimes on the fuel and then having to "pony up" for a *possible* $1000+ HG job. But that's a whole nother issue.... Quote Link to comment Share on other sites More sharing options...
nipper Posted July 30, 2007 Share Posted July 30, 2007 Recomended = for best performance, using regular is allowed but performance may suffer Required = you must use premium otherwise engine damage may occure and the warrenty will be void. Those are the standards. nipper Quote Link to comment Share on other sites More sharing options...
91LegLS Posted July 30, 2007 Share Posted July 30, 2007 96 OBW w/DOHC 2.5 phase 1 engine. Owner's manual recommends 91 Octane, but 87 can be used. In the almost 12 years and 222K miles on this car I have tried all types of octane and brand fuels. It basically runs fine on 87, the octane I used in the majority of it's life. It may ping once in awhile under load (going up a hill, fully loaded, etc). If you have occassional pinging from mid-grade fuel, you may want to consider removing the possible carbon build-up in your engine. Seafoam (heavily discussed here) BG 44K and other internal engine cleaning products may help reduce the need for premium. I use 87 octane in Denver driving up into the mountains (Vail Pass at 10,000 ft , Eisenhower Tunnel at the Continental Divide) and no hint of pinging ever. Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 30, 2007 Author Share Posted July 30, 2007 Remember to ask if the head gaskets have ever been replaced. While I like this engine, it has bitten quite a few people, myself included, in the pocketbook for HG replacement. Just don't want you to have expectations of saving nickles and dimes on the fuel and then having to "pony up" for a *possible* $1000+ HG job. But that's a whole nother issue.... Thanks, I think I know most of the pitfalls. What I'm looking at this point is an Impreza or Legacy between 95-99 with a 2.2 Recomended = for best performance, using regular is allowed but performance may suffer Required = you must use premium otherwise engine damage may occure and the warrenty will be void. Those are the standards. nipper Thanks Nipper! Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 30, 2007 Share Posted July 30, 2007 If you have occassional pinging from mid-grade fuel, you may want to consider removing the possible carbon build-up in your engine. Seafoam (heavily discussed here) BG 44K and other internal engine cleaning products may help reduce the need for premium. I use 87 octane in Denver driving up into the mountains (Vail Pass at 10,000 ft , Eisenhower Tunnel at the Continental Divide) and no hint of pinging ever. I've used Seafoam periodically, though not lately - big thumbs up on the product. I've also experimented with adding acetone to the fuel, which seems to make the engine run noticably smoother, especially in park/idle. The engine is due for some other tune-up items so Seafoam has been put on the to-do list again. Thanks. Quote Link to comment Share on other sites More sharing options...
jamal Posted July 30, 2007 Share Posted July 30, 2007 If you have occassional pinging from mid-grade fuel, you may want to consider removing the possible carbon build-up in your engine. Seafoam (heavily discussed here) BG 44K and other internal engine cleaning products may help reduce the need for premium. I use 87 octane in Denver driving up into the mountains (Vail Pass at 10,000 ft , Eisenhower Tunnel at the Continental Divide) and no hint of pinging ever. What, through magic? I'm not saying you shouldn't seafoam the car, but the compression and timing (and FI) are what determine the need for higher octane to prevent pre-ignition and detonation. You're not pinging with 87 because octane requirements go down as elevation increases since the air pressure is lower. Quote Link to comment Share on other sites More sharing options...
86BRATMAN Posted July 30, 2007 Share Posted July 30, 2007 What, through magic? I'm not saying you shouldn't seafoam the car, but the compression and timing (and FI) are what determine the need for higher octane to prevent pre-ignition and detonation. You're not pinging with 87 because octane requirements go down as elevation increases since the air pressure is lower. The magic of carbon build up increasing the compression ratio. You think that the carbon lining on the valves and pistons doesn't add up? Quote Link to comment Share on other sites More sharing options...
jamal Posted July 30, 2007 Share Posted July 30, 2007 hey that's good for more power then, right? Plus when the car is brand new it needs 91, how would seafoam change that? Quote Link to comment Share on other sites More sharing options...
firstwagon Posted July 30, 2007 Share Posted July 30, 2007 I know that was the year for preminum fuel I *really* have trouble with this. Subaru recommends premium fuel period (in all cars since 1990), why would you, or anyone else, have trouble with this? Here is what is going to happen: Knock sensor detects knocking, timing auto-retards, gas mileage drops 3-10mpg (depending on your driving habits), savings 0 (none), in fact it will cost you "real" money every visit to the gas station. Help me out please, because I really don't understand? In all cars??? I can't speak for all years but 1st gen Legacys (90 to 94) run on 87. That's what it says in the manual. I have tried premium on a few occasions (in the search for more power or mileage) and found no extra power and slightly worse mileage. Running premium in a car that doesn't need it is wasting money and at 11 to 12 cents a Litre (roughly 4 litres to the US gallon), it really adds up. That said, if the car really does need premium and you think it's going to be constantly bothering you, choice a different car. The 2.5 only needed premium for 1 or 2 years in the 90's so there should be lots to choose from that run 87. Quote Link to comment Share on other sites More sharing options...
86BRATMAN Posted July 30, 2007 Share Posted July 30, 2007 hey that's good for more power then, right? Plus when the car is brand new it needs 91, how would seafoam change that? I'm not saying it would change it, it is recommended for 96, right? I haven't read much on that year motor so I'm not sure if its required or not. But I've built motors for several different cars, and seen many different levels of build up on the pistons and heads. It really doesn't take much to increase compression by a few tenths, and a few tenths can be the difference between grades of ocatne level. Quote Link to comment Share on other sites More sharing options...
jamal Posted July 30, 2007 Share Posted July 30, 2007 Yes as far as I know 91+ is recommended for all 2.5s, and the STi needs 93. Quote Link to comment Share on other sites More sharing options...
91LegLS Posted July 30, 2007 Share Posted July 30, 2007 What, through magic? I'm not saying you shouldn't seafoam the car, but the compression and timing (and FI) are what determine the need for higher octane to prevent pre-ignition and detonation. You're not pinging with 87 because octane requirements go down as elevation increases since the air pressure is lower. Fuel sold in the Denver area compensates for higher elevation; we get 85, 87 and 91 octane. Unless fuel gets to be consistently $4 a gallon, I will never use anything below mid-grade. Super isn't worth the trouble unless my car was engineered for it, and even then mid-grade works just fine. It's like putting platinum plugs in a Model T. Whoop-de-freakin'-do. Quote Link to comment Share on other sites More sharing options...
elborak Posted July 30, 2007 Share Posted July 30, 2007 Yes as far as I know 91+ is recommended for all 2.5sUnless there's another reference in there that I'm missing (and I doubt it as I searched the entire document for "octane"), the PDF Owner's Manual for my '02 Legacy simply states "The 2.5 Liter engine is designed to operate using unleaded gasoline with an octane rating of 87 AKI or higher." Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 30, 2007 Author Share Posted July 30, 2007 Unless there's another reference in there that I'm missing (and I doubt it as I searched the entire document for "octane"), the PDF Owner's Manual for my '02 Legacy simply states "The 2.5 Liter engine is designed to operate using unleaded gasoline with an octane rating of 87 AKI or higher." As far as I know the only non-turbo Subaru engines that recommend premium are the MY96 2.5, and the 3.0L sixes and maybe the new 3.6L in the Tribeca. Carbon doesn't effect compression as much as cause heat retention (think pre-ignition or knock) and intake and exaust flow around the valves. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 30, 2007 Share Posted July 30, 2007 so what if you put a 98 outback ECU into a 96 LSi. would the different programing change the need for higher octane. or is the need in the mechanics?? Quote Link to comment Share on other sites More sharing options...
Suzam Posted July 31, 2007 Author Share Posted July 31, 2007 so what if you put a 98 outback ECU into a 96 LSi. would the different programing change the need for higher octane. or is the need in the mechanics?? Mechanics, the head on the MY96 2.5 were different than previous or post years. I'll see if I can find out what it was... in the interum, anyone else know the difference? EDIT: so far on cars101 for the MY 96: 2.5 Liter 155 hp, dual overhead cam, sequential multi-port fuel injected engine (new for 1996) and the MY97: New: 2.5 L now has 165 hp on regular unleaded gas instead of 1996's 155 hp on premium fuel. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 31, 2007 Share Posted July 31, 2007 Mechanics, the head on the MY96 2.5 were different than previous or post years. so far on cars101 for the MY 96: 2.5 Liter 155 hp, dual overhead cam, sequential multi-port fuel injected engine (new for 1996) and the MY97: New: 2.5 L now has 165 hp on regular unleaded gas instead of 1996's 155 hp on premium fuel. was it the heads that were different or the pistons with shorter skirts? would that alone be enough to increase from 155 to 165 hp ?? i know my 97 has it, any 96's out there with with piston slap??? Quote Link to comment Share on other sites More sharing options...
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