I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
91 vs 87 Octane
- Thread starter Eddie
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Perhaps it's for less knock retard, or to avoid running over rich using the fuel to cool? What are the CRs for the vehicles you mention?
We're currently at ~ 13% between the two octane ratings. Do these CUV/SUV's that you are considering allow for lower octane. IF NOT, you may have to stay with the high test!
wemay
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Very high compression ratios and relying less on knock sensors to deal with possible pre-ignition issues. I would venture to say that most of the vehicles you have researched are Direct Injection.
2012 and up Lexus RX does not require Premium.
Avoid it
Here in the bad days it was as high or higher than diesel.
I have a SUV and trust me regular gas makes life easily.
Of course Shell here has Premium Tuesdays at 20 cents off a gallon. However I'd rather have a diesel SUV- today its dirt cheap and tomorrow it will be premium priced but still a better alternative but none are as good as 87 octaner's
Here in the bad days it was as high or higher than diesel.
I have a SUV and trust me regular gas makes life easily.
Of course Shell here has Premium Tuesdays at 20 cents off a gallon. However I'd rather have a diesel SUV- today its dirt cheap and tomorrow it will be premium priced but still a better alternative but none are as good as 87 octaner's
Originally Posted By: Eddie
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
Just a thought, but a lot of these upscale vehicles are quite heavy due to all the extra sound deadening, safety, and electronic gizmos that they carry, which means they get terrible fuel economy. Wife's little Q5 weighs 4,350 lbs. I believe running premium fuel helps them improve MPG just slightly, and every little bit counts for those darn CAFE ratings. Most of these vehicles recommend premium, but allow you to run regular as well, with the caveat that you may lose some performance and your fuel economy may slightly decrease.
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
Just a thought, but a lot of these upscale vehicles are quite heavy due to all the extra sound deadening, safety, and electronic gizmos that they carry, which means they get terrible fuel economy. Wife's little Q5 weighs 4,350 lbs. I believe running premium fuel helps them improve MPG just slightly, and every little bit counts for those darn CAFE ratings. Most of these vehicles recommend premium, but allow you to run regular as well, with the caveat that you may lose some performance and your fuel economy may slightly decrease.
Higher octane fuels allow them to tune the engine to make more power more efficiently. Our 2005 MDX requires premium fuel. Sure, we can use regular. But, the engine doesn't run nearly as good and fuel economy does suffer. I wouldn't say that it suffers by 17%, so dollar-for-dollar, regular fuel is a better value. That said, I don't choose the fuel I use based on financial value -- I use the fuel that works the best.
All of my DI vehicles gets premium fuel in them because of the phenomenon known as LSPI ( low speed preignition). Until engine designers get that figured out that's the way it will be. DI engines tend to run well, which I like, so the the extra $$$$ is written off as the cost of doing business....
Originally Posted By: Eddie
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
There is "require" and there is "prefer" or "recommend".
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
There is "require" and there is "prefer" or "recommend".
Originally Posted By: Eddie
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
I doubt that its "prestige," its probably either from running a smaller engine at a higher BMEP to get the same output than the similar-sized competitors do, or simply an older cylinder head design that is more octane-hungry.
Just for grins, I looked up the RDX engine specs to compare to the Grand Cherokee (Pentastar v6, which I know uses 87 octane):
Torque
JGC- 260@4800
RDX- 252@4900
Horsepower
JGC- 290@6400
RDX- 279@6200
Compression
JGC- 10.2
RDX- 10.5
Curb Weight (Edmunds, 2015 numbers)
JGC- 4545 to 5151 lb
RDX- 3717-3852 lb
The RDX engine is a 3.5, so its 0.1L smaller (6 cubic inches). So they're operating in a very, VERY similar regime, so the higher BMEP guess is obviously wrong. It really is odd that the RDX requires premium.
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel. In my area premium fuel is 17% or 40 cents higher per gallon. When I review further, I find little in the way of HP or torque improvement over those models that only require 87 Octane. I think, the idea of spending the extra 17% is not the issue but, if there is no value added, what is the reason except prestige? Ed
I doubt that its "prestige," its probably either from running a smaller engine at a higher BMEP to get the same output than the similar-sized competitors do, or simply an older cylinder head design that is more octane-hungry.
Just for grins, I looked up the RDX engine specs to compare to the Grand Cherokee (Pentastar v6, which I know uses 87 octane):
Torque
JGC- 260@4800
RDX- 252@4900
Horsepower
JGC- 290@6400
RDX- 279@6200
Compression
JGC- 10.2
RDX- 10.5
Curb Weight (Edmunds, 2015 numbers)
JGC- 4545 to 5151 lb
RDX- 3717-3852 lb
The RDX engine is a 3.5, so its 0.1L smaller (6 cubic inches). So they're operating in a very, VERY similar regime, so the higher BMEP guess is obviously wrong. It really is odd that the RDX requires premium.
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If you have a vehicle that clearly states "premium unleaded fuel only",you do not want to run regular unleaded in it under any circumstances. Your engine will be pinging like crazy.
Originally Posted By: Eddie
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel.
This is what it says in RDX's owner's manual. I haven't checked the others:
Quote:
Fuel Information
- Fuel recommendation
Unleaded premium gasoline, pump octane number 91 or higher
Use of lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
It clearly states that it's just a recommendation and not a requirement. With that said, there will be some negative effects if you run lower octane fuel.
I was reviewing COVs & SUVs for possible future purchases. I noticed that the "Upscale" models like the RDX, Lexus and Infinity all "Require" premium fuel.
This is what it says in RDX's owner's manual. I haven't checked the others:
Quote:
Fuel Information
- Fuel recommendation
Unleaded premium gasoline, pump octane number 91 or higher
Use of lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
It clearly states that it's just a recommendation and not a requirement. With that said, there will be some negative effects if you run lower octane fuel.
I am fully aware of the Octane can be Premium only vs. Premium recommended. My CX5 Mazda suggests 87 octane to produce 184 HP from 2.5 liters and 185 ft./lbs. at 6,200 rpm. Something just doesn't seem to make sense to me with many of the "Upscale engines", requiring premium fuel.
Originally Posted By: Eddie
I am fully aware of the Octane can be Premium only vs. Premium recommended. My CX5 Mazda suggests 87 octane to produce 184 HP from 2.5 liters and 185 ft./lbs. at 6,200 rpm. Something just doesn't seem to make sense to me with many of the "Upscale engines", requiring premium fuel.
What was that "something"?
I am fully aware of the Octane can be Premium only vs. Premium recommended. My CX5 Mazda suggests 87 octane to produce 184 HP from 2.5 liters and 185 ft./lbs. at 6,200 rpm. Something just doesn't seem to make sense to me with many of the "Upscale engines", requiring premium fuel.
What was that "something"?
I think the stickers on fuel door of my cars(S2000, E430 and LS400) says: Premium Fuel Only.
I tried 87 and the performance did reduce substantial, especially when I went to Vegas in summer and tried to accelerate on 2-3 long steep hills when ambient temperature was above 120F.
I tried 87 and the performance did reduce substantial, especially when I went to Vegas in summer and tried to accelerate on 2-3 long steep hills when ambient temperature was above 120F.
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