What Fuel is everyone using?

[Brisoup1]

I'm pretty sure 89 is just 87 and 91 that is mixed at the pump. There's no seperate 89 tank.

That could be true, but older gas stations that have been running since the early 90's without pump/gas tank replacement very well could be mixing 87 & 93 fuel to make 89 octane at the delivery tanker.

 

[GerryS]

Understood, however it is backed by science. The origins of my knowledge on this are based on an article in a boating magazine. My father had numerous "Cigarette boats" growing up. Back then one of the popular workhorse motors was a Mercruiser 502. I believe it had 415 HP. Another was the Merc 500. Urban legend had tons of boaters putting premium in when the engine called for 87. It was so widely "known" that the engine ran better on premium that Powerboat magazine (I'm pretty sure it was them) did exhaustive tests on it. The result? Despite owners swearing up and down how it ran better, science proved it provided zero benefit, and in some cases the motor lost performance because it was running too rich (I think). This is very significant in the boating world when a small gas tank is 80 gallons, and many of these boats have 200-300 gallon tanks, getting less than 1MPG at speed.

I have read that fuels with higher octane levels actually decrease the power if the motor isn't tuned for it. I think higher octane fuels slow the burning process in the cylinder when the spark lights off the mixture. The result is that the maximum cylinder pressure is achieved after the piston is in the ideal position to make the most use of it. It has the effect of retarded timing in this case. (That may be one reason you use more advanced timing with higher octane, it brings the max cylinder pressure back to where the piston can take full advantage)

That being said, I believe the higher octane fuels have more additive packages that allow the gas to not break down as quickly over time. That might be why my lawn mower and snowblower recommend 93 octane fuel. (And it might be beneficial in a boat that sits in storage for an extended period.)

Gerry

 

[Barney556180]

I'm pretty sure 89 is just 87 and 91 that is mixed at the pump. There's no seperate 89 tank.

Back in the mid to late ‘60s, Sunoco heavily marketed its Wayne 511 custom octane pumps that blended two octane grades into five flavors: 190 to 260.

 

[SD Rebel]

In the owners guide, it says 89 octane is recommended but 87 octane is acceptable. It doesn't tell you why 89 is recommended.
ex: for max performance, better fuel economy etc.

The owners manual actually says the reason why. I don't like the fact the truck doesn't come with it but you have to request RAM to get an actual owners manual. The PDF download works well to.

 

[SD Rebel]

I have read that fuels with higher octane levels actually decrease the power if the motor isn't tuned for it. I think higher octane fuels slow the burning process in the cylinder when the spark lights off the mixture. The result is that the maximum cylinder pressure is achieved after the piston is in the ideal position to make the most use of it. It has the effect of retarded timing in this case. (That may be one reason you use more advanced timing with higher octane, it brings the max cylinder pressure back to where the piston can take full advantage)

That being said, I believe the higher octane fuels have more additive packages that allow the gas to not break down as quickly over time. That might be why my lawn mower and snowblower recommend 93 octane fuel. (And it might be beneficial in a boat that sits in storage for an extended period.)

Gerry

I think that applies to 100 octane or race octanes. 93 and 91 aren't enough to be an issue and probably within the tuning spec parameters.

 

[Brisoup1]

The owners manual actually says the reason why. I don't like the fact the truck doesn't come with it but you have to request RAM to get an actual owners manual. The PDF download works well to.

On my uconnect owners information screen, it didn't say why. Maybe I didn't look hard enough. What IS the reason why then?

 

[Tom488]

On my uconnect owners information screen, it didn't say why. Maybe I didn't look hard enough. What IS the reason why then?

From the owner's manual:

This engine is designed to meet all emissions regulations and provide satisfactory fuel economy and performance when using high-quality unleaded gasoline having an octane range of 87 to 89 as specified by the (R+M)/2 method. The use of 89 octane “Plus” gasoline is recommended for optimum performance and fuel economy.

While operating on gasoline with an octane number of 87, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see your dealer immediately. Use of gasoline with an octane number lower than 87 can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty.

Poor quality gasoline can cause problems such as hard starting, stalling, and hesitations. If you experience these symptoms, try another brand of gasoline before considering service for the vehicle.

 

[SD Rebel]

On my uconnect owners information screen, it didn't say why. Maybe I didn't look hard enough. What IS the reason why then?

It won't say it there, really skimpy info in these guides they gave us.

I would contact RAM customer support and request a hard copy, they will send you one, takes about a week, but I love reading the full manual.

But here is the PDF version https://5thgenrams.com/wp-content/uploads/2018/07/2019-RAM-1500_All_New-OM-3rd_R2.pdf

 

[GerryS]

I think that applies to 100 octane or race octanes. 93 and 91 aren't enough to be an issue and probably within the tuning spec parameters.

Could be true, but if the anti knock sensors aren't retarding the timing with 89, then using 91 or 93 will have no performance benefit. Of course, the premium fuel is sometimes advertised to have extra additives (Nitro+ etc.). More additives equals less BTUs per gallon.

Air temp also affects the likelihood for an engine to knock from low octane. The cooler the air, the less likely for it to knock. It might be worth it to use 89 when it's hot out in the summer and 87 would be fine in the winter?

Maybe my old obd2 scan tool will work on my Ram and I can see if there is a difference in ignition timing using 87 and 89.

Gerry

 

[SD Rebel]

Could be true, but if the anti knock sensors aren't retarding the timing with 89, then using 91 or 93 will have no performance benefit. Of course, the premium fuel is sometimes advertised to have extra additives (Nitro+ etc.). More additives equals less BTUs per gallon.

Air temp also affects the likelihood for an engine to knock from low octane. The cooler the air, the less likely for it to knock. It might be worth it to use 89 when it's hot out in the summer and 87 would be fine in the winter?

Maybe my old obd2 scan tool will work on my Ram and I can see if there is a difference in ignition timing using 87 and 89.

Gerry

We'll we aren't sure of that. We don't know if they tuned the perimeters to allow for an even higher increase if premium is used.

What I think I can safely say using 91 isn't going to harm anything and shouldn't cause a decrease in performance compared to 89 octane.

So if you had a choice of only 87 or 91, which is what us Costco buyers have, then 91 would be the best option, especially since it's already cheaper than most other stations 87. Going with 87 should reduce performance and mpg, while 91 won't.

 

[Biga]

We'll we aren't sure of that. We don't know if they tuned the perimeters to allow for an even higher increase if premium is used.

What I think I can safely say using 91 isn't going to harm anything and shouldn't cause a decrease in performance compared to 89 octane.

So if you had a choice of only 87 or 91, which is what us Costco buyers have, then 91 would be the best option, especially since it's already cheaper than most other stations 87. Going with 87 should reduce performance and mpg, while 91 won't.

Higher octane is not going to help mileage or performance if the vehicle does not tuned for it or require it. The only benefit is that some of the higher octane gas has better cleaning agents especially when you look at something like Shell V-Power.

 

[SD Rebel]

Higher octane is not going to help mileage or performance if the vehicle does not tuned for it or require it. The only benefit is that some of the higher octane gas has better cleaning agents especially when you look at something like Shell V-Power.

Yes, I agree. What I said is that we aren't sure what parameters are on the stock tune, if they do anything beyond 89, we don't know.

But my point is that using 91(due to it actually be cheaper in my scenario) isn't going to harm anything or lower performance compared to 89. And that it's better than using 87, since those are my only two octane choices. This is based off my choices at Costco, which are either 87 or 91.

Based on the stock tune, 87 will lower mpg and performance. 91 won't do anything different than 89 at the least.

 

[McBigHorn]

Mine was delivered from the dealer with a full tank of what I would wager is 87 and I've filled it once with the same. It drives like a champ. I'm not a performance driver, though, and just use it back and forth to work, store, and occasional light hauls. If maximum performance meant more to me, I'd probably go with 89 from a vendor that turns stock over regularly - but, actually, if it meant that much to me, I'd get a tune and likely run 91.

 

[Willwork4truck]

Ok now that weve beat this octane horse to death, lets discuss brand name fuels...

 

[Willwork4truck]

We'll we aren't sure of that. We don't know if they tuned the perimeters to allow for an even higher increase if premium is used.

What I think I can safely say using 91 isn't going to harm anything and shouldn't cause a decrease in performance compared to 89 octane.

So if you had a choice of only 87 or 91, which is what us Costco buyers have, then 91 would be the best option, especially since it's already cheaper than most other stations 87. Going with 87 should reduce performance and mpg, while 91 won't.

Just mix every half tank at Costco if you can.

 

[cra1g]

It seems like there's a temptation for a lot of people to do things "better" than what's recommended, without really understanding what "better" means. Top-Tier fuel is better; 93 octane isn't better, just different. Full synthetic is better; 10W-40 isn't better, just different. I bet I could make a fortune selling 13-volt batteries to these people.

 

[SD Rebel]

Just mix every half tank at Costco if you can.

Though I guess I could wait until I'm down half a tank and fill up with the other octane every other time, but I prefer to wait until I have a 1/4 left before filling up. Especially with how thirsty my Rebel is, I will be hitting Costco way too often at half a tank, not worth the couple of bucks I literally would save.

 

[Twoamen]

89

 

[Jtc411]

Speaking of uneducated, your reading comprehension must have had the night off

The study cited isn’t applicable to our vehicle mm’kay ?

Now try and follow along, some engines require premium fuel mm’kay?

So it matters

The recommendation from the manufacturer says to run 89 but you can run 87. Establishing there’s a difference

Has anyone run the 1500 on a Dino with two different octanes??

Until that happens there isn’t definitive evidence to suggest 87 doesn’t have long term effects or that 93 doesn’t garner max hp

However I’d be willing to bet a ribeye steak there is big time

Clarity and objectivity not bias and condescension

Your welcome

I don’t care if some cars require it. We’re talking about our cars. 89 is not required. It can be recommended all day long the statement made was using less than 89 would degrade the life of the engine. That is false. You can talk snarky all you want to “appear” intelligent but you completely botched your response. Have a good evening my friend.

 

[SD Rebel]

I don’t care if some cars require it. We’re talking about our cars. 89 is not required. It can be recommended all day long the statement made was using less than 89 would degrade the life of the engine. That is false. You can talk snarky all you want to “appear” intelligent but you completely botched your response. Have a good evening my friend.

That's true, it won't degrade the life of the engine. I think some comments are to if it will be worth it, since MPG is expected to drop. So if you calculate the mpg drop vs money saved, it may not be financially worth it to go with 87, plus you lose a little performance.

Though I honestly have not noticed any difference myself with mpg or performance with any grade.