I've seen in various threads people discussing using different grades of fuel, but no thread actually dedicated to it.

So, here's my question: For a stock (for now) 380, which fuel choice will give the best blend of fuel economy and longevity?

I know that in the US, engines will be able to 're-tune' to accommodate different fuel grades. However with some, the stock tuning is iffy, and they end up with more wear internally from poor combustion cycles. I'm looking to get the best fuel economy I can, without sacrificing lifespan on my engine by running a fuel that calls for a known iffy tune.

I've found 98/v-power/premium whatever you want to call it is the best I've had for fuel economy. And having a 380 means your ECU will auto advance the timing and will tune it back a bit if it knocks.

However the only issue is it's the most expensive.

Personally I run on corn now, smells amazing. Fuel economy is out the window though. lol

I've found 98/v-power/premium whatever you want to call it is the best I've had for fuel economy. And having a 380 means your ECU will auto advance the timing and will tune it back a bit if it knocks.

However the only issue is it's the most expensive.

Personally I run on corn now, smells amazing. Fuel economy is out the window though. lol

Indeed, corn ;)

The 380 6G75 motor is factory tuned to run on 91 octane ULP, but as Neo says it has a knock sensor (6G74 does not) and the ECU will adjust the timing to cater for higher octane fuel such as 95 or 98 PULP.
Lots of debate whether it's worth using 98 (Shell V-Power, BP Ultimate, Caltex Vortex etc) or not, in general the increased cost cancels out the slight improvement in fuel economy.
There is a bit of an improvement in power/torque/drive-ability as well, especially mid-range acceleration, but of course if you get carried away with the extra go you lose the improvement in fuel economy.
One of the main advantages of 98 is it contains more/better fuel system cleaning additives than 91.
The best compromise is probably to stick a tankfull of 98 in every 4th or 5th tank, that's all you need to keep the fuel system (especially the injectors) clean and happy.

Indeed, corn ;)

Distilled corn, he means (I think) - maybe E10, or 100% ethanol? It does tend to give the exhaust a nice aroma!

Prefer fermented fossil dinosaur droppings myself. (Scientifically more accurately described as "fossil fuels", or "liquid hydrocarbons".)

Yea E85

Car loves it. Advanced timing across the board etc.

When my wagon is done being built I'll strip down my current TF Sedan (aka the beast) and check out the fuel system components. Not expecting to see any wear from the E85.

I gave 91 a go when I first bought the 380 but went back to 95/98 pretty quickly. Definitely runs better on the good stuff. The main thing I noticed was heading up hills - with 91, it would labour and eventually knock back a gear. 95 or 98, it will hold the higher gear and maintain speed without too much difficulty.

As to what type of fuel... BP Ultimate is best imo, but I will usually go for whatever is cheapest or most convenient.

Yea E85

Car loves it. Advanced timing across the board etc.

When my wagon is done being built I'll strip down my current TF Sedan (aka the beast) and check out the fuel system components. Not expecting to see any wear from the E85.

So how many km do you get to the bushel of corn?

I only use 98, but i only drive the beast on weekends so i don't take much of a hit at the pump when i fill it up. I drove the SIII Platinum up from Coldtoria 2 1/2 years ago and it ran like a dream all the way, didn't miss a beat and was smooth in all driving conditions. That sealed it for me, and that was in a completely stock vehicle. I'm going to make a few mods now on the VRX. 90mm intake, K&N filter, straight through muffler to start with and i'm really looking forward to the experience. I've used a lot of E10 premium and it goes ok, but i notice it uses more in any driving situation, especially in suburban stop-start driving. You'll pay more for the 98 but i think the engine labors less and it's far smoother at all rev ranges.

ULP91 is fine on a 380.

Can't honestly say I can feel the difference in normal driving.

I find the BP98 significantly better than the V power or other variants.

E10 makes my 380 stink in the garage so I don't use it.

I've tried the 100 octane premium-max with 5% ethanol, also didn't like that.

Best thing I've done for power and economy is Morey's Upper Cylinder Lubricant in each tank. Drops my instantaneous consumption at 60km/hr in 5th from 6.0 to 5.0. Temp gauge sits lower. I used to use it in my old Camry which had 300k on the engine, but when I bought my brand new 380 I didn't bother. Tried it a few months ago and haven't looked back.

Honestly, I've only ever used 91 in all of my cars since I've had a license.

Caltex 91 is all I ever use and I can't really fault it.

So how many km do you get to the bushel of corn?

With 95 I used to get anywhere from 9.7 - 11 around town only. On corn it's sitting at 12.7. Not bad considering it's using a fair bit more fuel because of the lower energy.

It's moreso a requirement for a major upgrade coming very soon.

9.7-11 around town is better than the 13-14 I am getting on 91, and probably enough better to justify the higher fuel cost, since almost all of my driving is urban.

E85 is also 5-6c cheaper than 91 so it's ok. I might go fill up with 85 later for 94c/litre :D

Yea, I'm just very leery of running E85 in an engine tagged E10. My grandfather did that with his Chevy Silverado in the US, and it did not end well.

Not too many cars are rated for E85. Magna and 380 aren't, I'm sure.

Yea, I'm just very leery of running E85 in an engine tagged E10. My grandfather did that with his Chevy Silverado in the US, and it did not end well.

Yea most GM cars, Holden's and Ford's don't handle it well at all, cheaper fuel system components as well.


Not too many cars are rated for E85. Magna and 380 aren't, I'm sure.

Rated? The components will handle it fine as some quick research will show. Magna's, Lancers, Galants/Legnums have been running fine on stock fuel system components.

The ECU using the stock ROM however... but some quick reprogramming and the computer handles it fine. I need a wideband (soon™) to do some refinements of my AFRs for maximum efficiency.