TheSubaruJunkie Posted September 12, 2006 Share Posted September 12, 2006 So ive been b1tchin to the guys at work about how my car has been pinging. And last week I was so broke, I had to force myself to fill the RX up with 87 octane instead of the usual 91 (saved $0.20 a gallon). So, since then, the car has developed some major hesitation and pings like crazy. Im an entry level mechanic at a new shop. I work with 5 other veteran mechanics who all know their shiz, and one of them suggested I run 1gal of diesel at fillup to increase the octane. I laughed at him, and refused to do so... but he swears by it. He said a friend of his did it to his VW and helped stop all the pinging he experienced. Anyone here have any wisdom to share on this subject? -Brian Quote Link to comment Share on other sites More sharing options...
daeron Posted September 12, 2006 Share Posted September 12, 2006 never heard of that... a buddy's dad once had to rebuild his engine because a gas station somehow screwed things up bad enough that diesel was in the regular tank... or coming out of the pump, or something. simply topping off with some good ol fashioned 93 octane oughta do ya... around here all the stations sell is 87. 89, and 93.. and they only have two tanks. the 89 is a blend of the two. 91 is achieved the same way. Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted September 12, 2006 Author Share Posted September 12, 2006 No 93 here, only up to 91. -Brian Quote Link to comment Share on other sites More sharing options...
MilesFox Posted September 12, 2006 Share Posted September 12, 2006 i would use kerosene. about a gallon or 2 for a full tank. we used it when roberts car got stuck in the river Quote Link to comment Share on other sites More sharing options...
Qman Posted September 12, 2006 Share Posted September 12, 2006 So ive been b1tchin to the guys at work about how my car has been pinging. And last week I was so broke, I had to force myself to fill the RX up with 87 octane instead of the usual 91 (saved $0.20 a gallon)....-Brian I too have been really broke and thought I might save by using lower grade fuel. Never diesel or kerosene and wouldn't. Those are both used for cleaning parts and maybe, just maybe, that is the benefit of using either one. Go read some octane boosters in the parts store and see what they are made up of. Think of this though, @ $.20 a gallon for a fill up of 10 or even 20 gallons is only saving $4.00. Is it worth the frustration and poor performance? Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted September 12, 2006 Share Posted September 12, 2006 not something i'd do, you might check into acetone though. Diesel is an oil, more so than a fuel per-se, and your car won't run on it straight, so if there is any seperation you may not have a running car. Try cleaning the carbon deposits out with a good old seafoam treatment. Also, diesels run Cetane, not Octane, so its a totally different category. Quote Link to comment Share on other sites More sharing options...
Qman Posted September 12, 2006 Share Posted September 12, 2006 never heard of that... a buddy's dad once had to rebuild his engine because a gas station somehow screwed things up bad enough that diesel was in the regular tank... or coming out of the pump, or something. simply topping off with some good ol fashioned 93 octane oughta do ya... around here all the stations sell is 87. 89, and 93.. and they only have two tanks. the 89 is a blend of the two. 91 is achieved the same way. Maybe in the south that math would work. We in the PNW have 3 tanks at our stations. Better yet, maybe you could show us some documentation to that effect. Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted September 12, 2006 Author Share Posted September 12, 2006 Think of this though, @ $.20 a gallon for a fill up of 10 or even 20 gallons is only saving $4.00. Is it worth the frustration and poor performance? It will have to this week, as Im so broke that $4 will buy me dinner tonight. Tomorrow, i dunno what i'll eat. Also, diesels run Cetane, not Octane, so its a totally different category. Thats what I was thinking too. You dont see octane ratings on diesel, so I didnt think it would work the same mixed with Unleaded. I think im gonna remove my injectors and send them off to be cleaned. Hoping that might help the performance side of things. Just gotta get more money in the bank, payday is Friday -Brian Quote Link to comment Share on other sites More sharing options...
daeron Posted September 12, 2006 Share Posted September 12, 2006 down south?? its a simple matter of 3 parts to 2... (2x93)+(3x87)=447. 447/5=89.4. if there are three tanks, then theyve got diesel. ask the guy who owns your local independent gas station... the lackeys pushing buttons at the corner shell wouldnt know the 5 button from a hole in their head, but the owner operators will tell you how much they pay for gas if you know how to ask them. they will give you your documentation. how many times have you seen a fuel truck with three hoses on the ground? then again, maybe its genuinely different. certainly a non zero possibility. all i know is that at the port of palm beach, there are two biiiiiiig fuel tanks. ones for 87 octane, the other for 93. all the chain stations put their own proprietary detergents etc in after they get it from the port. this has been confirmed by three different station owners for me now, so i know its the truth here. Quote Link to comment Share on other sites More sharing options...
calebz Posted September 12, 2006 Share Posted September 12, 2006 Added suggestion. A number of the WRX/STi people around here are using an E85 mixture in their Subarus. Couple of gallons to a tank E85/93 octane mixture.. Substantially higher octane rating. Perhaps the math could work out with a Regular/E85 mixture. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted September 12, 2006 Share Posted September 12, 2006 Added suggestion. A number of the WRX/STi people around here are using an E85 mixture in their Subarus. Couple of gallons to a tank E85/93 octane mixture.. Substantially higher octane rating. Perhaps the math could work out with a Regular/E85 mixture. Hhhhmmm - isn't E85 pretty corrosive to older rubber's and such? I'm not sure what it would do in a diluted state but I'm also not sure I would want to try it without doing a few bench tests with hoses and o-rings and such. I would hazzard a guess that most if not all of the newer rubber compounds being used for automotive applications (ie: WRX's) is rated for it already.... GD Quote Link to comment Share on other sites More sharing options...
SuBrat84 Posted September 12, 2006 Share Posted September 12, 2006 If you filled up with 15 gallons at .20 a gallon you would save 3 dollars. Why would you then spend that 3 dollars for a gallon of diesel? Or a gallon of anything else for that matter? If you're really that hungry go find a food bank. Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted September 12, 2006 Author Share Posted September 12, 2006 Im talking about for the future, when im not so broke. I wont ever fill my RX with 87 octane again. Not after driving the past 3 days with it. And if I bought 1 gallon of diesel, that means I would only have to buy 14 gallons of Unleaded. And right now, diesel is cheaper than premium... so I wouldnt be wasting any money at all. The kicker is, nozels that pump diesel wont fit in my gastank, so i couldnt even put a gallon of diesel in my tank even if i wanted to :-p -Brian Quote Link to comment Share on other sites More sharing options...
4x4_Welder Posted September 12, 2006 Share Posted September 12, 2006 Diesel won't damage an engine without electronic controls. It may foul the plugs if you use too much, or the O2 sensor, and may not burn completely if your engine doesn't need the extra resistance to explosion. Done warning, here's real life: I used to run 10% diesel in my 84 F-250. The engine (300-6) was at better than 9.5:1 compression, maybe closer to 10.5:1, and pinged at 6º on 93 octane. The diesel stopped it from pinging with mid-grade, and probably saved the engine. On the other hand, I was also running an HEI ignition, a .060" plug gap, and 9.8mm solid core wires for about a 60kv spark at idle, upwards of 85kv at higher rpms. Don't run any blend of ethanol over about 10% in a car not designed for it. It will eat the rubber in the hoses, if it's something with a mechanical fuel pump, it will eat the fuel pump, and you will lose a lot of mileage due to the lower energy content. Quote Link to comment Share on other sites More sharing options...
JTMCO Posted September 12, 2006 Share Posted September 12, 2006 As the octane rating of gasoline goes down, it is more prone to auto-ignition. That is why your car started to ping when you changed to 87 octane. Diesel fuel is designed to autoignite. In other words, to some extent you want a diesel engine to ping. So I think putting in diesel fuel will only make it worse. Your choices are: 1.) Clean any carbon out of you cylinders with Seafoam or similar. The carbon gets hot and promotes autoignition. 2.) Retard your timing a little bit. 3.) Bite the bullet and buy 93 octane. The other (impractical) option is to somehow decrease your compression ratio. Good luck. Jim Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted September 12, 2006 Author Share Posted September 12, 2006 As the octane rating of gasoline goes down, it is more prone to auto-ignition. That is why your car started to ping when you changed to 87 octane. Duh!! 3.) Bite the bullet and buy 93 octane. See above... note: 93 is not available in Sacramento... The other (impractical) option is to somehow decrease your compression ratio. Why would i do that, after spending 4 months building my motor using higher compression pistons? -Brian Quote Link to comment Share on other sites More sharing options...
4x4_Welder Posted September 12, 2006 Share Posted September 12, 2006 Actually, diesel oil is far more thermally stable than gasoline, and burns rather than explodes. Diesel engine burn their fuel over about 25º or crank rotation, versus about 15º for a gas engine. Diesels only make their trademark banging noise becuase the pistons are set with zero pin offset (with the exception of a few modern engines), and the fuel gets injected at 5-8º BTDC. The fuel lights off instantly, since the air in the combustion chamber is over 1000ºF, and it is injected as an incredibly fine mist. Quote Link to comment Share on other sites More sharing options...
Davalos Posted September 12, 2006 Share Posted September 12, 2006 I swear, I learn more here than I did in school! I just picked-up a gallon of Acetone ... trying it for mileage - I'll report back with my results ... Quote Link to comment Share on other sites More sharing options...
4x4_Welder Posted September 12, 2006 Share Posted September 12, 2006 I have experimented with acetone on a different vehicle, it helps with pinging, but don't use more than a couple ounces per tankful. You will only see an increase in mileage if you car has a knock sensor, or you can safely increase the timing without it pinging. Quote Link to comment Share on other sites More sharing options...
hotrod Posted September 12, 2006 Share Posted September 12, 2006 Don't run any blend of ethanol over about 10% in a car not designed for it. It will eat the rubber in the hoses, if it's something with a mechanical fuel pump, it will eat the fuel pump, and you will lose a lot of mileage due to the lower energy content. That is an overly broad statement and is not correct. If you run over 10% ethanol you won't be covered under warrantee --- not many of us driving older subies have to worry about that. It will not eat the rubber hoses if the car was manufactured after the early 1980's. All manufactures switched to ethanol compatable fuel lines, O-rings and fuel system components at that time. (there were some isolated issues with older cars pre-1976 with non-ethanol compatible fuel lines etc. For example the fuel hoses on my 1969 VW did not play nice with ethanol) The modern Subies run very well on blends of E85 and gasoline. I have run up to 50% blend in my 88GL but that was a bit too lean. It hesitated a bit, but other wise ran fine on the highway with slightly better power. It did very well on lower blends (around 30%). In the WRX it will run on up to 30% with a noticable improvement in performance. 30% - 50% the car runs very well with a strong improvement in performance but it triggers a CEL. With larger fuel injectors it "LOVES" 100% E-85. On 100% E85 the WRX got 92% of the milage per gallon it did on straight gasoline, but cost per mile dropped due to the lower total fuel cost. I will be converting my 86 GL-10 to run on E85 here in the next year or so. Larry Quote Link to comment Share on other sites More sharing options...
LPGsuperchargedBrumby Posted September 12, 2006 Share Posted September 12, 2006 i've run fuel contaminated with diesel (result of a tanker driver filling the wrong tank on a friends farm...1000ltrs of petrol with about 50ltrs of diesel mixed in) i started to get suspisious when i put 4L of oil in the brumby and got 5L out at the next oilchange@5000km <<<< i thought i had a real money spinner there,my own oil well on wheels. i figger that the diesel just wasn't burning, it was washing down past the rings into the crankcase. diluted oil is not cool i told my father about it and he said that his father had exactly the same thing happen to him in the early seventys in his VW 1200....must be something to do with the flat fours:headbang: Quote Link to comment Share on other sites More sharing options...
mikie Posted September 12, 2006 Share Posted September 12, 2006 i've run fuel contaminated with diesel (result of a tanker driver filling the wrong tank on a friends farm...1000ltrs of petrol with about 50ltrs of diesel mixed in) i started to get suspisious when i put 4L of oil in the brumby and got 5L out at the next oilchange@5000km <<<< i thought i had a real money spinner there,my own oil well on wheels. i figger that the diesel just wasn't burning, it was washing down past the rings into the crankcase. diluted oil is not cool i told my father about it and he said that his father had exactly the same thing happen to him in the early seventys in his VW 1200....must be something to do with the flat fours:headbang: I had the almost identical experience a few years ago, using diesel/petrol mix in an old cortina. The difference is that my engine got thirsty, started using oil and had to be changed shortly after. I also figured bore wash thanks to the diesel. The octance rating of diesel is 25 (RON) according to wikipedia. I dont think id ever use it in a petrol engine again, but ive tried normal ethanol, complete with purple colouring, and at 5% it makes a noticable difference in a turbo vehicle, ping-be-gone. At 10% (as high as ive been willing to try) i was able to advance the timing for an additional 20 rwkw, a 10% power increase, over normal petrol. Quote Link to comment Share on other sites More sharing options...
Hondasucks Posted September 21, 2006 Share Posted September 21, 2006 The car probably ran better due to the detergent effect of the diesel cleaning out the combustion chambers Quote Link to comment Share on other sites More sharing options...
beataru Posted September 21, 2006 Share Posted September 21, 2006 Ive fueled aircraft for a "school intership" from small aviation up to kingairs 350's (which take jetfuel (JET A) which is a higher cetane number than diesel... still smells terrible... untill you burn it:grin: yummy) and i learned somthing there--- diesel will freeze if in cold climates even at the runway so.. inorder to keep that from happening they make JET-B Which is Blue-100low-lead mixed with about 80% jet fuel. soo the question is.... do you wana tryit because it will work Viceaversa? My personal opinion is that it will work, but, your fuel filter is going to be hurting badly because diesel has extreemly large particulate matter (well microns but still!) compared to gasoline-also diesel has the chance to get bad bacteria that gumup your diesels performance-- """so for all of you diesel runners out there.. if your diesel smell like someone took a crap in the fueltank tell the gas station you want your money back!""" so after my huge sharade which probably was meaningless- It will work in small quantitys.. dont do half and half or even 60-40 or even... you know what i mean.. a tiny bit also... the diesel nozzle wont fit in your fuelhole, its bigger,(probably already knewthat) so bring something to wipe the side of your car down because it gets everyware! wow i got real carried away hehe Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 21, 2006 Share Posted September 21, 2006 do NOT try this. I personally have seen what diesel does to gas motors. only one gallon is enough to make it run like crap or not at all. I have seen it at work mutiple time and accidentally added some contaminated(diesel) fuel to my truck once. they smoke and run like crap. pinging is actually worse than normal and performance (if it still runs) is terrible. tell new guy to try it on his car first. Quote Link to comment Share on other sites More sharing options...
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