Fellow Q45ers…I know we are all struck with this maddening gas price hike. For me it’s especially a struggle because my Q is also my road-trip vehicle. And on the EPA site, I’m estimated to only be getting 22 mph highway and 17 city. But I think it’s even lower than that.

Lately, I just been putting mainly mid grade with the occasional premium for a top off. However, I’m currently in an area that regular gas is 85, and the manual for both my maxima and q45 do not recommend going that low, even for higher elevations. So 87 is “mid grade” in this area, with the 91 being premium which is often an extra $0.40-60 cents more than regular.

I know some will say, “well if you can’t afford a V8 get something electric/4 cylinder”, but that’s just not doable. I think the prices going to be inconvenient no matter what you drive, but I’m just wondering if I run midgrade or regular, what are some things I can do to “maintain”? Would I need to change oil and spark plugs more often? Has there been any actual reports of a q45 being damaged by excessive use of regular?

Anything over $3 a gallon starts to become an issue I find.

I also have a V8 and its an SUV to boot.
I thinkin a lot of locations midrange if you just drive gently should be fine.
About your higher elevations fuel.. if you are actually at those higher elevations you should be fine with the lower octane just be sure to fuel up with higher octane when back in the flat areas.

Pretty much it is what it is. Speeds at 70+.

The big difference is when I drove 800 or more miles I always arrived relaxed, comfortable and fresh. Do not trash your engine with low octane gas.

maxnix wrote: ↑

Sat Apr 02, 2022 3:46 pm

Pretty much it is what it is. Speeds at 70+.

The big difference is when I drove 800 or more miles I always arrived relaxed, comfortable and fresh. Do not trash your engine with low octane gas.

Yes, I always stress a bit when I gassed up the Pathfinder with less than premium. calculating in my head what the octane rating in the tank should be right now.
Of course many mid range fuel listed as 89 Octane are really 90. at least in the East.

I used 89 on a pure highway trip at low elevations last year. No issues. Its the only time I've done it but its really just not worth it in the long run. Use sparingly if you do and be easy on the pedal.

If the sticker inside the fuel door says "Premium Fuel Required" then using anything less is risking engine damage due to detonation - the compression ratio of the engine requires the higher octane to prevent predetonation, and the ECU can't reduce timing enough to prevent it. If the sticker says "Premium Fuel Recommended" then using lower octane is possible but the ECU will be retarding the ignition timing to prevent predetonation which means the engine will be running less efficiently, getting worse fuel mileage, and making less power.

Side note: you think you're not getting the advertised MPG you should be - first: calculate your actual mileage over a couple tanks so you know your mileage instead of guessing, and second: if the fuel mileage IS low, tune it up and repair whatever is causing the low fuel mileage in the first place.

Many people waste money putting in higher octane gas in cars that are not designed to run anything other than regular. I never ran anything less than 91 in my Q45 (sold in 2019) and literally never had an issue with my engine. I ran nothing but 91 in my 84 300ZX or it knocks, it was designed to run on regular unleaded gas (there was really no premium in 84), but I drive it so little doesn't matter. My 05' Nissan XTerra I only put 87 in and for sure it makes zero differnce running anything higher (tried mid-grade and premium a few times no difference in performance or gas mileage).

I would say your not smart regularly runnning lower octane in a Q45, do the real math on what 17 gallons or premium costs vs. midgrade or regular...maybe $5 to 7 bucks for a fill-up max. Now do the math on replacing knock sensors, coil packs and having your enginer go downhill faster.

If your car says use premium, use it. Not worthwhile for the shorterm small savings vs. the long term issues you can create. Now if you plans are to sell the car soon who cares, but if your long-term owner keep it at 91+

Since you brought it up, it reminds me of a 95 Q45a that was up for sale nearby about a year ago that i looked at. I met the owner at a local community park, and the first thing I noticed was the way the engine sounded. It was knocking so bad that it barely idled, sound was horrible. If you stick to Top Tier gas station mid-grade it should be fine. They usually add better additives, some of which are specifically for anti-knock. There's the dilemma, though- Top Tier mid-grade cost about what premium does elsewhere. Can't win for trying.

Most Nissans in the OBD2 era have a "Target Timing Adjustment" you can use to dial back on the need for premium fuel. Of course you'll lose some power and there are a few caveats that affect tune-up time, but the NDS-3 app will get you into it on most Nissan/Infiniti ECM's. See this post:
post6838664.html

Forgot to get back on this one, but thanks for all the replies.

Yeah it definitely seems like a drop in the bucket debating regular versus premium. But in some states, they really stick it to you on the difference. I don’t live there, but I know when I visit Wisconsin and Illinois, it can be nearly 80, 90 cents more. And when you’re talking 15 gallons to fill up (I never seem to bottom out at the full 21 gallons to fill up)…that can easily be an extra $12 to fill up. And if it’s not the cost that’s noticeable, you’ll notice only getting 3/4 tank when it should be full.

I also noticed: the fuel economy.gov has dropped the highway mileage of the Q from what I remember being 25 to about 22: though it seems to be from user submitted resources:

https://www.fueleconomy.gov/feg/noframes/14323.shtml

That said: sometimes I try to avoid it by filling up with regular halfway on 1 tank, and then premium on the next. Or Midgrade only, or Midgrade and premium. Depending how expensive or cheap regular is where I am. Sometimes I can’t resist when it’s $3.15 for regular and 3.95 for premium. That’s not a couple bucks. That’s paying $3 versus $4.

I know one thing I won’t use again: is E15%. Did it in another vehicle, just a few gallons. Was having sputtering and acceleration issues as the tank went lower. Thought I could balance it out evenly but seems the alcohol went to the bottom of the tank.

Honestly I’m just so over it. I already feel fossil fuels we need to get away from anyway. There’s sun and water, and wind for free. I know cars don’t care for any of those (except wind), but I just feel cheated in life that we have to pay to run a vehicle. Gas shouldn’t be a financial burden, insurance and car repairs are enough lol.

However, I’m also talking from someone who went from 185,000 miles to 325,000 miles over a course of 4 years. So, I couldn’t even tell you how much I’ve spent on gas. Only break I had is when I filled up for $18 in 2020 and during the Main lockdowns of Covid.

Let's be honest the Q45 in all 3 generations got horrible gas mileage. My brother had a 96' Lexus LS and he got better mileage, the LS switched over to a 5 speed and Q's didnt until 2002 3rd gen. My dad's 92 was a beast but that car couldn't get 20 MPG for me ever, my 97' was a little better, got 24-25 if you were on a mostly level road going under 70 MPH. When I was looking for the next luxury boat I wanted V8 power but didn't want to pay V8 prices at pump. Sold my 97' and bought 16' Mercedes S-Class Plug-in Hybrid. I can use all electric for short trips and combine I get around 32-36 MPG, but still need super unleaded, but tank only holds 15 gallons so less painful. I hope in a few years to replace that with a much longer range electric, my wife has Nissan Leaf which we use all the time now super cheap to operate.

Everyone wanna be a ballah, until it's time to do ballah stuff...

LOL, I had to google what Ballah was.......nice one Skibane!

I will admit that I've filled my Q with 87, 89, and 91 with no discernible difference in performance.