89 octane recommend, does it really make a difference?

[theblet]

What is the compression ratio on the 5.7 hemi? And has anyone tried an octane booster/fuel additive?

 

[Neurobit]

I’ve used 87 a couple of times, but 89 almost always. Did a few tanks of 93 for a few months and did not notice any difference in performance or MPG, so I went back to 89 and it will be that way until I sell it.

Cheers,

 

[HSKR R/T]

What is the compression ratio on the 5.7 hemi? And has anyone tried an octane booster/fuel additive?

You will spend more money on adding enough octane booster to make any worthwhile difference than if you just bought the hugher octane fuel out of the oump.

 

[HSKR R/T]

I’ve used 87 a couple of times, but 89 almost always. Did a few tanks of 93 for a few months and did not notice any difference in performance or MPG, so I went back to 89 and it will be that way until I sell it.

Cheers,

If anything you would have a decrease in mileage and performance runnjng a higher octane than what the computer is tuned for. In this case, anything higher than 89oct won't help.

 

[TravisJ]

If anything you would have a decrease in mileage and performance runnjng a higher octane than what the computer is tuned for. In this case, anything higher than 89oct won't help.

This would be the best answer for this question. There should probably be some kind of difference between 87/89, but past that nothing.

I have always been a minimum required kind of guy, unless towing. All that extra money at the pump really adds up. I find it hard to believe using 87 versus higher octane that is recommended is going to harm my vehicle. If it does, after about 100k miles I will have thousands I saved on gas to pay for it. However, it is just like oil changes. Some people think they are doing their vehicle some kind of favor replacing oil every 4-5k miles. People can treat their vehicle however they choose.

 

[41magmag41]

I always use 89 from Irving but if Im near a sams club i fill her with 93 because its usually 30 t0 40 cents cheaper than the irving mid grade. Only use regular in a pinch. Winter blend gives me 16/17 mpg, summer blend is coming back and I get 18.5/21 mpg depending on driving style.

 

[Dadeoo]

Well, this is a fun thread to watch as an ecodiesel owner. When I had a Durango with a 5.7 hemi I noticed no mileage or performance difference between regular and mid-grade. Mileage sucked either way, knocking occurred when towing with regular grade. Towing a travel trailer I got 9 MPG, not towing about 18. No matter what.

NOW, when I use diesel #1 in winter there's a real difference. Mileage drops noticeably, but its still better than what I got with the Hemi. Not towing, I now get "only" 23 or so MPG on diesel #1, 28 or so when on D#2. Towing numbers are a bit more than half those numbers.

So there's that.

 

[Neurobit]

Well, this is a fun thread to watch as an ecodiesel owner. When I had a Durango with a 5.7 hemi I noticed no mileage or performance difference between regular and mid-grade. Mileage sucked either way, knocking occurred when towing with regular grade. Towing a travel trailer I got 9 MPG, not towing about 18. No matter what.

NOW, when I use diesel #1 in winter there's a real difference. Mileage drops noticeably, but its still better than what I got with the Hemi. Not towing, I now get "only" 23 or so MPG on diesel #1, 28 or so when on D#2. Towing numbers are a bit more than half those numbers.

So there's that.

That’s awesome MPG, even with winter fuel.

 

[90goldtsiawd]

If any of you don't know or understand what knock/detonation is you should probably look it up. Use the 89 octane like recommended and don't cheap out on the long term life of your engine.

 

[IvoryHemi]

What is the compression ratio on the 5.7 hemi?

10.5:1

 

[silver billet]

If any of you don't know or understand what knock/detonation is you should probably look it up. Use the 89 octane like recommended and don't cheap out on the long term life of your engine.

I've come to the conclusion that half the world is deaf

 

[TravisJ]

If any of you don't know or understand what knock/detonation is you should probably look it up. Use the 89 octane like recommended and don't cheap out on the long term life of your engine.

Or one could just use 87 and use the saved money for a warranty. Over 125k miles, assuming you get a 1mpg bump with 89, you would save around $1,750 over those miles (depending greatly on difference in price of 87/89 in your area). For that cost you can go get a 7/Unlimited or 8/125k powertrain warranty. Then everything is covered on the powertrain regardless if it is caused by worse gas or not. If there is no gas mileage gain between the two you could probably afford a 8/125k bumper to bumper warranty.

Of course I am not one to own my truck 10+ years or put on 200k miles, so it is different for everyone.

 

[90goldtsiawd]

Or one could just use 87 and use the saved money for a warranty. Over 125k miles, assuming you get a 1mpg bump with 89, you would save around $1,750 over those miles (depending greatly on difference in price of 87/89 in your area). For that cost you can go get a 7/Unlimited or 8/125k powertrain warranty. Then everything is covered on the powertrain regardless if it is caused by worse gas or not. If there is no gas mileage gain between the two you could probably afford a 8/125k bumper to bumper warranty.

Of course I am not one to own my truck 10+ years or put on 200k miles, so it is different for everyone.

Ytf would you wanna compare possibly saving pennies on the dollar in the long run buying a $2k to $3k+ extended warranty to risk blowing the motor and having to deal with that just to spend a few dollars less per fill up at the pump? It's not like you're buying a used 1988 Toyota Tacoma, these are $50k +++ pickup trucks. I don't think anybody who can afford one should be worrying about the savings from 87 to 89 octane fuel, otherwise you probably shouldn't have bought the truck in the first place.

 

[SD Rebel]

Ytf would you wanna compare possibly saving pennies on the dollar in the long run buying a $2k to $3k+ extended warranty to risk blowing the motor and having to deal with that just to spend a few dollars less per fill up at the pump? It's not like you're buying a used 1988 Toyota Tacoma, these are $50k +++ pickup trucks. I don't think anybody who can afford one should be worrying about the savings from 87 to 89 octane fuel, otherwise you probably shouldn't have bought the truck in the first place.

Used 88' Tacomas probably cost that much, lol.

Definitely agree with your statement, though I don't think in the short term 87 would hurt your engine, since the manual clearly states it's acceptable, but I don't think it will save you money in the long run and also who knows could lead to issues in the long term, with more engine deposits could lead to more knocking on 87 and some people just don't notice it.

It says in the manual that light knocking on 87 is ok, I rather not have any knocking at all.

 

[TravisJ]

Ytf would you wanna compare possibly saving pennies on the dollar in the long run buying a $2k to $3k+ extended warranty to risk blowing the motor and having to deal with that just to spend a few dollars less per fill up at the pump? It's not like you're buying a used 1988 Toyota Tacoma, these are $50k +++ pickup trucks. I don't think anybody who can afford one should be worrying about the savings from 87 to 89 octane fuel, otherwise you probably shouldn't have bought the truck in the first place.

A powertrain warranty is only about $1,500 for 8/125k.

There is a pretty good chance in 125k miles the truck doesn't blow up cause 87 octane was used. Why not insure against 87 octane blowing up your engine AND any other reason anything on the powertrain might blow up? If I am going to spend an extra $1,500 why not insure the entire powertrain for any reason? No worries then.

Again, if you are keeping your truck for the next 10+ years and putting 200K on it maybe you want to use 89...I won't be so I am not really concerned about long term effects of 87 fuel.

 

[silver billet]

A powertrain warranty is only about $1,500 for 8/125k.

There is a pretty good chance in 125k miles the truck doesn't blow up cause 87 octane was used. Why not insure against 87 octane blowing up your engine AND any other reason anything on the powertrain might blow up? If I am going to spend an extra $1,500 why not insure the entire powertrain for any reason? No worries then.

Again, if you are keeping your truck for the next 10+ years and putting 200K on it maybe you want to use 89...I won't be so I am not really concerned about long term effects of 87 fuel.

I was towing my trailer last summer and got caught in a small town with just regular gas on one side of the pump and an out of order "supreme" on the other. Filled up and headed back home, got to some largish hills on the freeway and I swear I was seconds away from blowing a rod. Slowed down and moved over just to reduce that pinging, had a sick feeling in my stomach the rest of the way home.

Not every one is towing every day, but the proof is in the pudding, these trucks kinda need 89+. That's on a brand new hemi with < 15,000 KM on the gauge at the time.

Running 87 and working it hard is hemi abuse.

 

[doolin64]

I ran two tanks with 89 and noticed no difference. I went back to 87 and still achieve the same $h!tty gas mileage. LOL

 

[90goldtsiawd]

Most of the time you won't "notice" any knock/detonation unless you're datalogging with some sort of fuel management system in any car, but that doesn't mean it's ok and not having any detrimental effects. If you can actually hear/feel it happening that's probably bad.

 

[theblet]

From the manual. Does this mean don't use seafoam? I usually put a can every oil change. 1/2 into the vac line of the brake booster, and the other half in the tank.

Indiscriminate use of fuel system cleaning agents should beavoided. Many of these materials intended for gum andvarnish removal may contain active solvents or similaringredients. These can harm fuel system gasket anddiaphragm materials

 

[brian42]

Yes, that is what the Owner's Manual is saying. Use recommended fluids, use Top Tier gas (preferably 89 octane), and don't use any additives.

FCA is obviously being conservative as they have not tested their systems against active ingredients in additives. There are so many with ingredients in different combinations and concentrations that they are saying "don't do it" as they don't have any data to show if it has a positive, neutral, or negative effect.

I used to use additives regularly in my previous vehicles. Since I've jumped to this truck (my last truck was a 2003) there is so much technology that I have no idea what any additives will do to the systems. Since I bought the truck new I am sticking to the higher end of the product spectrum (Pennzoil Ultra Platinum engine oil, Top Tier 89+ octane gas, etc.) and not using any additives.