Premium Fuel vs. Regular Fuel question and Vehicle Dynamic Control question

If you start out by putting regular and continue to put only regular in you'll be fine. Higher octane fuel is just recommended because it helps to prevent the engine knocking/engine pinging in high performance engines. So you could use regular and be fine cause it would adjust to that. However, if you went from premium to regular it would mess with the engine and you would just damage it over time.

As long as the 3.5L is not forced induction, using reg unl fuel is ok. The computer is able to compensate and retard timing to correct any detonation issues caused by using lower octane fuel giving the engine is not forced induced.

The vehicle has a 10.3 to1 compression ratio... On the lower end of high compression motors... My geuss is that they the engine with a fairly advanced timing curve in order to recomend higher octane fuel. Likely the car will retard the timing in order to prevent engine damage, however you'll likely loose both power and efficiency using cheaper fuel, negateing the minuscule savings of running regular... I believe the '09 is suppose to get 21 mpg... so lets say using regular losses you a barely noticeable 1.5 mpg due to a retarded timing curve.... so 92.86% of normal engine efficiency... We'll say base line cost is 3.70 per gal... so premium we'll say is 4.00 even... regular is 92.5% the price... 0.36% diffrence between loss of mileage and cost savings between useing premium and regular. If you have a station nearby that still does 10 cent increments between grades instead of 15 cent ones it would be cheaper to use premium... at best you're saving 2 cents per gallon, so why bother? This is negating the fact that even with a retarded timing you may experience occasional pre-detonation which would prematurely wear the engine, and that premium fuel usually has more detergents added to keep your engine clean. Long story short... Just get the premium, there is almost no noticable change in cost to you between premium and regular, even if your car didn't loose efficiency, if it didn't it'd be more likely to ping resulting in wear and damage, it's only a few dollars per tank. I mean do you really think the manufacturer puts that rating on there for fun? It's not like it helps sell cars...

Thanks for the info. I'm in Florida. Gas here right now is @3.87/gallon Regular, @4.20/gallon Premium. Also, what do you think about Dynamic Vehicle Control? The 2009 requires Tech package to get it. What does it gain me?

VDC is a safety feature and keeps the car under control. It doesn't really give you performance gains. When it's on, it controls the brakes and the throttle. So, for example, if you're taking a turn too fast, it will apply a little bit of the brakes so you don't lose control of the car. If you're accelerating too hard while the car is in a turn, it will reduce the amount of throttle that is available to you. From what I've read, it's very subtle and you won't notice it too much...unless you're going WAY too fast and/or jerk the steering wheel suddenly, at which point the car might not have time to react and save your crazy ass. :D

I don't know about the fuel mileage thing, but if you're strapped for cash at one fill-up, using regular should be fine, the engine will just retard the timing (to the best of my knowledge) Also, VDC really isn't needed because the car tends toward nice, safe understeer anyway. However, if you tend to drive crazy fast and/or in slippery conditions, I'd say VDC would be helpful.

what ive learned is that if you use regular that u jave to use fuel injector cleaner and u can buy that anywhere and that will do just about the same as using premium. most cars say use premium bc all it has is the cleaner and other cleaners but i think its cheaper to buy these cleaners ur self instead of using premium everytime and u dont have to use the cleaners everytime u can use them every other fill up or 3000-30000 miles for some.

The cleaners are just an added benefit mate. engineers don't take those into account since not all stations have added detergents in the premium fuels. It is there for one of two reasons... An advanced timing curve where more controllable spark propagation is necessary or in a high pressure (forced induction or high compression motor) where the pressure can cause the fuel charge to detonate prematurely resulting in excess wear and potentially engine damage.

it wont damage the engine by putting regular if its supposed to take premium. thats one of the reasons that cars have computers on them, to help manage the engine and adjust for the octane provided. my car is supposed to take prremium but for 4 years it ran on middle. onlyh this year i started putting premium in it and its fine because the computer adjusted for it.

I wasn't saying it would damage the engine. I stated that it may cause detonation to occur. I also said it may happen if you went from premium to regular not the opposite way around. I am indeed aware of the fact that the computers in a car are there to help it adjust for lower octane. The chances simply increase a tad that something may happen in the event you go from premium to regular.

A friend here at work indicates if the manual indicates Premium and I use Regular, it could void the engine warranty. Can that happen?

It depends on the component... For example if any part of your fuel system goes out they can't blame the fuel since there is no correlation between octane level and wear on fuel components... Bad news is they can say it caused knock and void warranty on your rotating assembly, all relevant bearings, the valve train, head gasket, cams, and any related mechanical systems. They can only void warranty on related parts, that would have been affected by the use of low grade fuel. IE anything that would undergo excess strain when the engine pings... (sorry I realize I kinda flip flop pinging=pre-detonation=knock... although knock is usually misleading so I'll try to stick to one of the first too)) It'd take a real super prick to check your gas tank if the head gasket blew though. There really isn't much of a cost variance though, so you should only use it once in a blue moon anyway and then you should never get a full tank, just enough to get to the next time you have $3-5 more to get a tank of premium... It's really not much more expensive, so why is it an issue. A more relevant and costly question would be the regular maintenance schedule? Does the engine require synthetic over regular oil due to thermal properties? How often must the coolant be flushed? Will I have to deal with a transmission flush, if so how often? All these are worth more time than worrying about if you can put regular in... You talking of spending thousands of dollars on the car, but not being willing to spend a few buck more a week.

Thank you all for your GREAT input. Currently, I drive a 2002 Saturn SC1 coupe (bought in Oct 2001) and plan on getting the Altima coupe (probably the V6, Premium package)in October/November. To be on safe side, I'll do the Premium gas. Like a friend said "Penny Wise can be Pound Foolish", i.e. trying to pinch pennies can, in long run, be detrimental. This is a GREAT forum / website!

My 1997 Altima runs aweful on High octane, 89 burns much better or slightly easier it seems and ignites better, my idle is about 200 to 300 higher and stalls less on 89 as well.. and it was stallling alot after 150,000 miles, despite changing the ignition, distributor, cap, rotor, wires, plugs, O2 sensor, gas filter...and Still stallled alot and lost power even at 70mph! LOWER OCTANE helped more than all those repairs! Don't use premium! Try 89!

I feel if you value your high performance engine, like the 3.5 SR Nissan Coupe's engine & the manual requires Premium fuel, then I do it. I'm picking up my Nissan Altima 3.5 SR coupe tomorrow, and it's getting only Premium octane fuel. The saying goes like this, pay it now or pay it later if you damage the car's engine. Also, yes the auto maker could not cover a engine having used the wrong fuel. Pay it now , or pay more later, come on, we are talking penney's here. It's your car, it deserves the finest I feel.

Hmmmm…. I have a 2016 Altima with the 3.5 V6 and the manual says: use "87 octane AKA" which means anti-knock. I was using middle-grade but now I'm switching to regular because it saves 40 CENTS per gallon, which is about $7 per fill-up. Wish me luck!

In our 2009 V6 Maxima, the owners manual advises to only use premium unleaded, but if premium is not available, to fill tank only partially with reg unleaded, and fill up with premium as soon as possible. It also says to avoid full throttle driving and abrupt acceleration (when reg gas in tank). I noticed after using reg gas for a couple of months, and some rapid acceleration a couple of times, there seems to be a slight vibration at maybe 40 mph - so I am going to go back to premium or maybe midrange

Will a tank overspill (i.e. automatic shut off at K-T pump didn't work) harm the engine on a 3.5L 6 cyl 2010 Infiniti? If so, is there anything I can do to limit harm to the engine/fuel system?

I have a 2006 Nissan Altima 2.5 - I have experimented with Premium VS Regular unleaded. I can definitely tell a difference in how it runs. Much smoother on Premium. Doesn’t seem to kick down in the hills as much with Premium, just pushes through. With regular it has to kick down a gear on inclines. Also idles smother, don’t feel the engine running like you do with regular (smother and quieter).

I just got 2019 Nissan Altima I put high grade gas in the first day should I go to regular

Which engine your car has matters. Is it the turbo version? I talked to a guy who ran his V6 Altima to 190K miles... he always added one of those fuel injector cleaners of 2-3 oz. at every fill-up; they make a large bottle too with a measure on the side. I do that every tank full. We will see....it runs smoother