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Wondering if anyone could give me the heads up in regards to gas to use in my 350Z. Previously had a maxima that I only used regualr unleaded in instead of the premium unleaded like was plastered all over the gas cap and manual and never had one problem (turned 200,000 miles last week)....does this hold true for the 350z? Don't want to push my luck but no need to pay the extra if there really is no need....thanks
 

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The car should run fine on the regular unleaded gas I've read in quite a few places that people run regular unleaded and have no problems, however it is better for the engine if you run the higher octane. IIRC the computer in the car will adjust itself to the different fuel, but you'll definitely get better performance from the premium.
 

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Don't be a cheapskate, put the premium in. If you run regular you will get knock under load or during high outside ambient temps. The ECU will pull timing, performance will be impacted.

Trust me, car makers don't want to have to specify premium because it negatively impacts sales. So rest assured, when they tell you to put in premium they generally aren't kidding.

Ronin Z
 

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Don't be a cheapskate, put the premium in. If you run regular you will get knock under load or during high outside ambient temps. The ECU will pull timing, performance will be impacted.

Trust me, car makers don't want to have to specify premium because it negatively impacts sales. So rest assured, when they tell you to put in premium they generally aren't kidding.

Ronin Z
+1
 

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There are reasons why the owners manual says to put premium. The Z's engine is high compression which requires higher octane. Pay the extra couple dollars per tank.
 

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Aloha,
In the short term, it seems economically good.........pennywise, pound foolish. The engine will start to build up deposits and you will start to see performance and mileage issues. BTW, cheap premium is also not a good idea. Chevron, Shell, 76, the "name" brands have additional additives (detergents) to help keep the fuel system clean, and fuel to burn better. If you're using Costco gas, be sure to use a fuel additive at least once every two or three fill ups.

A Hui Hou

PaulO

ps. when your lady needs a drink, don't you buy her "topshelf"?
 

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Wondering if anyone could give me the heads up in regards to gas to use in my 350Z. Previously had a maxima that I only used regualr unleaded in instead of the premium unleaded like was plastered all over the gas cap and manual and never had one problem (turned 200,000 miles last week)....does this hold true for the 350z? Don't want to push my luck but no need to pay the extra if there really is no need....thanks
If you can't afford to run your car on the good stuff, you'd be better off selling the car and buying another econobox than running it on shithouse fluids.

Its a sports car, and it runs better on higher performance products. If the high performance thing doesn't interest you, why bother driving a car so unsuited to commuting?
 

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If you can't afford to run your car on the good stuff, you'd be better off selling the car and buying another econobox than running it on shithouse fluids.

Its a sports car, and it runs better on higher performance products. If the high performance thing doesn't interest you, why bother driving a car so unsuited to commuting?
+1, seriously this post goes along the same lines as people upset when they only get 20K miles on tires. Why would someone buy a sports car and then see what they can get away with that will compromise performance?
 

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You get 20K miles on tires!?!!?

The most I've ever gotten out of a set of tyres is around 15K miles, on DZ101s. My first two sets of RE040s lasted around 10K miles each (but I did do track days on them, the DZ101s only did 1 track day.....and that was in the wet so I spent all day drifting).

I'm quite happy that I've managed to get around 10K miles out of my current RT215s, which still have a reasonable amount of tread. I haven't been particularly nice to them either, but once again no track days.
 

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Without a doubt run the recommended octane. Sports car, moderately high compression and rev limit, you don't want the thing to start knocking or take the chance of it. The extra couple bucks is well worth it. On the flipside going to a higher octane rating than recommended will likely result in a decrease in performance, though at no danger to the engine internals.
 

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On the flipside going to a higher octane rating than recommended will likely result in a decrease in performance, though at no danger to the engine internals.
That isn't true, the gas just burns cleaner.. usually resulting with better gas mileage (I heard a little hp boost even.. I'm not sure)

91-94 octane is recommended for premiums in the US, in Japan it's 96-98.
 

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I've never tried it for myself, but friends of mine, including one who does engine/ECU development for Bosch Automotive, have told me running higher octane than necessary can bring down power output. I know a buddy of mine years ago, in HS of all things, did a test and found running 93 in a car that needed 85 gave him worse mileage. Not exactly a controlled test though.. The higher octane number just means it takes more activation energy to get the process going, so it would seem to make sense to me that for each combustion reaction with higher octane fuels you will be spending more of the available energy just starting the reaction, and unless you're upping the thermodynamic efficiency of the process going with a higher compression ratio you lose out a little in the end.

I suppose it really depends what the fuel composition is.. and I have no idea what Shell vs Conoco vs Sunoco vs whatever all put in their fuel. I imagine if you're just upping octane rating with some xylene or toulene maybe you wind up with more BTU's per gallon overall?

I do know that if you're actually blending gas with n-heptane and iso-octane, iso octane burns either less readily or slower and you lose some combustion efficiency.

A chemist would know this crap way better than I...
 

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I find it rather funny that I see lots of people w/ G's and Z's here in California filling up with 89 octane to save a couple bucks.

(FYI - There's three octanes in Southern California: 87, 89, 91)
 

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I've never tried it for myself, but friends of mine, including one who does engine/ECU development for Bosch Automotive, have told me running higher octane than necessary can bring down power output.
Depends on how good the ECU is.

Modern ECUs technically should be able to adjust their timing. It constantly monitors the knock levels, and if it notices the engine isn't knocking then it'll advance some more, until it gets enough knock to trigger it to "pull back". So theoretically it should make more power.

The OEM will specify a minimum octane level, so it can run a certain amount of timing and deliver the advertised power. However, if the ECU cannot dynamically adjust its mixtures and timing based on sensor inputs enough to cope, then yes going to a higher octane fuel can reduce power.

In some cases it can actually cause knocking. I remember hearing stories about how the first well-selling Hyundai Excel in Australia had issues where people running it on 95RON were breaking their engines. The owners bought the premium fuel thinking it was cleaner, more efficient, and more power producing than the OEM mandated 91RON. However, since the ECU couldn't adjust its timing (not sure if it just didn't have a knock sensor, or if the ECU wasn't advancing the timing enough) the thing ended up with some of the fuel not igniting. This meant the effective A/F ratio was lean and it was dumping a fuel-rich gas into the exhaust and clogging the cat up, a double whammy when it comes to robbing power, and after a while the engine knocked itself into oblivion.
 

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Go with the premium, for the best performance and mileage. Using the cheap stuff will give poor gas mileage. Once had to get the 89 and only got 26 mpg, but with the 93 it's 27.5 - 28 mpg all day long. Highway of coarse.
 

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Don't be a cheapskate, put the premium in. If you run regular you will get knock under load or during high outside ambient temps. The ECU will pull timing, performance will be impacted.

Trust me, car makers don't want to have to specify premium because it negatively impacts sales. So rest assured, when they tell you to put in premium they generally aren't kidding.

Ronin Z
What RON is your "premium gas"?
 

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My 2005 350z requires 93 Octane gasoline. Ive had mine 2yrs. Performance of the car is recomended. Im alawys joking " My pay neva goes up but My Gas price is a EXPENSIVE place to go...
 

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Man thank you guys so much i been running my 350z on 89 but as soon as i vet close to empty its 91 forever baby i dont mind paying cluoke extra bucks for a longterm engine 🎉
 
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