I run the best and highest octane premium fuel in everything I own and have for many years. Currently using top tier Shell 93. Starting doing this when I asked my former brother in law why he used only premium fuels in all his gasoline powered equipment on his farm (he had a lot of machinery and had a 1000 gallon tank on his property). He said that it was his experience and those of other farmers in the region that machinery ran better, lasted longer and "did more work per gallon" with premium fuel. I believed it then and still do.
Premium fuel reducing oil fuel dilution effect?
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Sure would be nice to have some real data rather than educated guesses. I'm not sure if can be done without lab quality instrumentation but, could the fuel consumption vs engine speed & load be plotted for octane level? That type of data could correlate fuel octane to hp/fuel consumed vs fuel in oil. Ed
The Owner's Manual specifies 87 octane for my 2.4L non-turbo GDI. When the car was new, I tried regular vs premium and noticed very little difference in mpg or performance. At 23,000 miles, however, the premium offered noticeably more pep and the +2mpg paid for the additional price of the premium. Perhaps carbon buildup is the reason why there is now a difference. I will continue using premium since it is cost-effective and might well reduce the possibility of LSPI events.
It seems logical that a higher octane fuel which prevents ignition retardation would burn more completely. I may use premium in a DI engine but it makes no sense to do so in a port injection engine unless you're racing stoplight to stoplight. A double digits price premium to gain 1% in fuel economy isn't logical. Top tier gaslolines have the same additive package accross the board so there is no difference in "quality".
My own opinion.
There is no advantage to premium fuel unless your car manufacturer calls for it. Higher octane fuels run dirtier and that's why they have to have extra cleaners. You may be slightly better mileage with high octane fuels but not enough to justify the cost. Fuel dilution? Wouldn't higher combustion pressures, from advanced timing, force more gases past the rings?
There is no advantage to premium fuel unless your car manufacturer calls for it. Higher octane fuels run dirtier and that's why they have to have extra cleaners. You may be slightly better mileage with high octane fuels but not enough to justify the cost. Fuel dilution? Wouldn't higher combustion pressures, from advanced timing, force more gases past the rings?
Higher octane fuels have larger hydrocarbons in the blend (more energy) which may not burn as completely but will result in a longer combustion phase prior to the exhaust valve(s) opening which might cause a more complete and cleaner combustion. I'm not sure where the trade-off is. There can be some performance benefits to higher octane gas in engines due to the knock sensor.
Originally Posted By: WobblyElvis
My own opinion.
There is no advantage to premium fuel unless your car manufacturer calls for it. Higher octane fuels run dirtier and that's why they have to have extra cleaners. You may be slightly better mileage with high octane fuels but not enough to justify the cost. Fuel dilution? Wouldn't higher combustion pressures, from advanced timing, force more gases past the rings?
You're correct for port injected engines of nominal 8-9.5:1 compression ratio that dominated for 20-30 years. Unless you made changes to the engine to take advantage of the premium it rarely if ever would increase power & economy enough to justify the expense.
Whats going on is since these GTDI engines are running so much pressure they would risk detonation, so in order to try to combat this they run rich if you feed them 87 to try and cool the combustion chambers. Since there is excessive fuel not all of it vaporizes, and some of it lands on the cylinder wall. First of all, the piston is going down on the intake stroke during injection. If not every little bit of the fuel that landed on the swept bore of the engine vaporizes before the piston comes back up on compression, the rings will wipe it, and some fuel will make it past them.
Second thing is, liquid unleaded doesnt go bang. It has to vaporize into a mixture with air. A fuel/air bomb if you will. So any liquid the rings might have pushed up will not burn fully either providing more time for fuel to leak past the rings.
I mean we are talking about such a small amount of fuel escaping during a single cycle its almost immeasurable. If it was a ml of fuel past the rings every combustion cycle on every cylinder you'd fill the crankcase and have raw fuel coming out the dipstick tube in a few miles.
Giving it premium really is giving these GTDI engines the fuel they were designed for. They can run hotter and leaner, promoting better vaporization of the fuel. The OEMs will tell you you can run 87 because they want you to buy the car, and for many people, having to spend an extra $.30/gallon for premium is a deal breaker. So they program these engines to accommodate that. So what if the fuel in the lube causes higher timing chain wear, higher piston ring wear, or whatever? It'll last through the warranty period; thats all they care about.
My own opinion.
There is no advantage to premium fuel unless your car manufacturer calls for it. Higher octane fuels run dirtier and that's why they have to have extra cleaners. You may be slightly better mileage with high octane fuels but not enough to justify the cost. Fuel dilution? Wouldn't higher combustion pressures, from advanced timing, force more gases past the rings?
You're correct for port injected engines of nominal 8-9.5:1 compression ratio that dominated for 20-30 years. Unless you made changes to the engine to take advantage of the premium it rarely if ever would increase power & economy enough to justify the expense.
Whats going on is since these GTDI engines are running so much pressure they would risk detonation, so in order to try to combat this they run rich if you feed them 87 to try and cool the combustion chambers. Since there is excessive fuel not all of it vaporizes, and some of it lands on the cylinder wall. First of all, the piston is going down on the intake stroke during injection. If not every little bit of the fuel that landed on the swept bore of the engine vaporizes before the piston comes back up on compression, the rings will wipe it, and some fuel will make it past them.
Second thing is, liquid unleaded doesnt go bang. It has to vaporize into a mixture with air. A fuel/air bomb if you will. So any liquid the rings might have pushed up will not burn fully either providing more time for fuel to leak past the rings.
I mean we are talking about such a small amount of fuel escaping during a single cycle its almost immeasurable. If it was a ml of fuel past the rings every combustion cycle on every cylinder you'd fill the crankcase and have raw fuel coming out the dipstick tube in a few miles.
Giving it premium really is giving these GTDI engines the fuel they were designed for. They can run hotter and leaner, promoting better vaporization of the fuel. The OEMs will tell you you can run 87 because they want you to buy the car, and for many people, having to spend an extra $.30/gallon for premium is a deal breaker. So they program these engines to accommodate that. So what if the fuel in the lube causes higher timing chain wear, higher piston ring wear, or whatever? It'll last through the warranty period; thats all they care about.
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I wonder if running rich (which it supposedly does with regular) is the way the manufacturer is trying to combat LSPI - basically just "flooding" the combustion chamber with extra gas to avoid the possibility of the spontaneous combustion. And since with premium gas engine will run leaner could that potentially inhibit the LSPI? well, at least increase the possibility of the LSPI happening?
Originally Posted By: parshisa
I wonder if running rich (which it supposedly does with regular) is the way the manufacturer is trying to combat LSPI - basically just "flooding" the combustion chamber with extra gas to avoid the possibility of the spontaneous combustion. And since with premium gas engine will run leaner could that potentially inhibit the LSPI? well, at least increase the possibility of the LSPI happening?
AFAIK the current research is that the fuel doesnt really matter for LSPI and its the oil primarily that is causing it. When the piston is coming up on compression some small amount of oil hanging out on the cylinder wall or piston ring decides its had enough and lights off like a diesel which then sets off the fuel air charge early.
Running rich combats 'regular' type knocking where its the fuel/air mix itself deciding to compression ignite or some hot spot in the cylinder triggering it. Hoewever I think they are still trying to get the lock down on the LSPI issue.
I wonder if running rich (which it supposedly does with regular) is the way the manufacturer is trying to combat LSPI - basically just "flooding" the combustion chamber with extra gas to avoid the possibility of the spontaneous combustion. And since with premium gas engine will run leaner could that potentially inhibit the LSPI? well, at least increase the possibility of the LSPI happening?
AFAIK the current research is that the fuel doesnt really matter for LSPI and its the oil primarily that is causing it. When the piston is coming up on compression some small amount of oil hanging out on the cylinder wall or piston ring decides its had enough and lights off like a diesel which then sets off the fuel air charge early.
Running rich combats 'regular' type knocking where its the fuel/air mix itself deciding to compression ignite or some hot spot in the cylinder triggering it. Hoewever I think they are still trying to get the lock down on the LSPI issue.
wemay
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2013 Santa Fe 2.0L T-GDi
I've never noticed a difference in MPG or power when using 93 versus 87. I switched to 93 octane after seeing how much soot was on my spark-plugs during the first 40K mile change. After the next 40K miles on strictly 93 octane and only synthetic oil? Exact same thing. Since that second plug change I fuel up with whatever i feel like using at the moment, 87/89 or 93. The Hyundai still runs like the day it was bought, great.
The Sonata 2.4L GDi has only recieved 87 octane.
I've never noticed a difference in MPG or power when using 93 versus 87. I switched to 93 octane after seeing how much soot was on my spark-plugs during the first 40K mile change. After the next 40K miles on strictly 93 octane and only synthetic oil? Exact same thing. Since that second plug change I fuel up with whatever i feel like using at the moment, 87/89 or 93. The Hyundai still runs like the day it was bought, great.
The Sonata 2.4L GDi has only recieved 87 octane.
Ok. figured I'd share it with you. Sa far had 3 tanks of premium burned and oil level seems to be settled now around 1/16" lower than it was with regular gas. No gasoline smell to it. I've performed an oil drop test and the result is quite interesting: gasoline ring (transparent external ring indicating gasoline being present in the oil) is completely GONE. I've done drop tests in the past whenever I was using regular gas and they all indicated gasoline in the oil (1/8" thick ring, fuel dilution confirmed by UOA). Of course, this is not the most accurate way to test the oil for fuel dilution although can be used to access it's condition. Another 1900mi. Or perhaps I'll just pull the sample now and send it to the lab. Really rally curious to see if higher octane fuel helps with fuel dilution in this particular engine. Hope y'all find this interesting as well
Originally Posted By: parshisa
Ok. figured I'd share it with you. Sa far had 3 tanks of premium burned and oil level seems to be settled now around 1/16" lower than it was with regular gas. No gasoline smell to it. I've performed an oil drop test and the result is quite interesting: gasoline ring (transparent external ring indicating gasoline being present in the oil) is completely GONE. I've done drop tests in the past whenever I was using regular gas and they all indicated gasoline in the oil (1/8" thick ring, fuel dilution confirmed by UOA). Of course, this is not the most accurate way to test the oil for fuel dilution although can be used to access it's condition. Another 1900mi. Or perhaps I'll just pull the sample now and send it to the lab. Really rally curious to see if higher octane fuel helps with fuel dilution in this particular engine. Hope y'all find this interesting as well
Mind sharing the drop tests pictures of one premium fuel vs regular fuel ?
Ok. figured I'd share it with you. Sa far had 3 tanks of premium burned and oil level seems to be settled now around 1/16" lower than it was with regular gas. No gasoline smell to it. I've performed an oil drop test and the result is quite interesting: gasoline ring (transparent external ring indicating gasoline being present in the oil) is completely GONE. I've done drop tests in the past whenever I was using regular gas and they all indicated gasoline in the oil (1/8" thick ring, fuel dilution confirmed by UOA). Of course, this is not the most accurate way to test the oil for fuel dilution although can be used to access it's condition. Another 1900mi. Or perhaps I'll just pull the sample now and send it to the lab. Really rally curious to see if higher octane fuel helps with fuel dilution in this particular engine. Hope y'all find this interesting as well
Mind sharing the drop tests pictures of one premium fuel vs regular fuel ?
Originally Posted By: parshisa
Unfortunately, I didn't keep "regular" sample, sorry. With that said you'll have to take my word for this
Not doubting your position.
I believe it's clearer to 'see' presence/absence of fuel dilution phenomenon in drop tests rather than BStone uoa.
Unfortunately, I didn't keep "regular" sample, sorry. With that said you'll have to take my word for this
Not doubting your position.
I believe it's clearer to 'see' presence/absence of fuel dilution phenomenon in drop tests rather than BStone uoa.
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I can confirm that it does help with fuel delusion using Premium fuel in some engines. My 2014 Mazda 3 is one example. Lots of UOA of the Skyactiv engine show fuel in the oil. Mine shows none and I run strictly Premium.
I believe it advances the timing and allows for a more complete burn.
I believe it advances the timing and allows for a more complete burn.
Originally Posted By: parshisa
Yeah, I honestly was extremely surprised to see what I saw. As of now (without polaris UOA confirmation), all the facts are telling me that premium fuel does help with fuel dilution in this particular engine!
That's a real bummer, you buy a good but average sedan, not a performance or luxury vehicle and it needs premium fuel, not for performance but for maintenance reasons. I did an UOA for our Ford 2.3 EB, using Mobil 1 5W-30, driving 7,000 miles in 2 months using a mix of premium and mid grade fuel this past summer. No fuel dilution was in the UOA or other indications of fuel dilution in the UOA. I'm currently running Motorcraft 5W-30 for 5,000 miles using only regular fuel. I'll do an UOA in January when it reaches 5,000 miles. This will give a more realistic UOA with "normal" everyday driving. While my oil smelled somewhat of fuel when I changed it the oil level did not increase and my wear metals were fine. PS, Premium fuel by me ranges from $0.50/gallon to $0.80/gallon more than regular.
Whimsey
Yeah, I honestly was extremely surprised to see what I saw. As of now (without polaris UOA confirmation), all the facts are telling me that premium fuel does help with fuel dilution in this particular engine!
That's a real bummer, you buy a good but average sedan, not a performance or luxury vehicle and it needs premium fuel, not for performance but for maintenance reasons. I did an UOA for our Ford 2.3 EB, using Mobil 1 5W-30, driving 7,000 miles in 2 months using a mix of premium and mid grade fuel this past summer. No fuel dilution was in the UOA or other indications of fuel dilution in the UOA. I'm currently running Motorcraft 5W-30 for 5,000 miles using only regular fuel. I'll do an UOA in January when it reaches 5,000 miles. This will give a more realistic UOA with "normal" everyday driving. While my oil smelled somewhat of fuel when I changed it the oil level did not increase and my wear metals were fine. PS, Premium fuel by me ranges from $0.50/gallon to $0.80/gallon more than regular.
Whimsey
I just figured the cost of 93 octane over 87 right now where I am in Virginia is about 40 cents more per gallon. I converted that to about 1.2 cents per mile more by getting 30 mpg in my ecoboost Mustang. Yes, I cruise and try to keep it light footed and try to get good MPGs. Anyway, premium fuel costs 40¢ more than regular. Ends up costing 1.2¢ more per mile. So, 5000 miles costs $60 more in gas. Or $12 per 1000 miles. DIY oil changes cost $30 so, you can use 87 octane, save $36 (at 3000 miles) by not using premium gas and do oil changes at 3000 miles and save more money and have fresher, cleaner oil! Of course, if 87 octane gas is ruining our engines by diluting fuel in oil, ruining oil additives, ruining timing chains and ruining pistons and rings, 93 octane is better and costs less! Time will only tell that.
We all want our engines/cars to last. Here is a link to a F150 ecoboost that has 385,000 miles on it. Link is for last page of thread at the time of posting this. Look at the last post on this page. No mods, no catch can and did oil changes at 6k to 7k. https://www.f150ecoboost.net/forum/...-300-000-miles-my-2011-eco-boost-14.html
We all want our engines/cars to last. Here is a link to a F150 ecoboost that has 385,000 miles on it. Link is for last page of thread at the time of posting this. Look at the last post on this page. No mods, no catch can and did oil changes at 6k to 7k. https://www.f150ecoboost.net/forum/...-300-000-miles-my-2011-eco-boost-14.html
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