Unioil EURO 5 Gasoline/Diesel

**Dr.Kamiya** · December 6th, 2019 06:05 PM

Originally Posted by Egan101

You are talking about a WRX STI and your weekend tuned toy car. Of course, there will be some gains in performance.

For the usual gas-fed cars with small displacement engines on factory tunes and a 91RON requirement, a higher octane fuel will not have significant gains.

But you specifically said "Subaru Turbocharged Engines". I was just replying to that claim.

Right now the set of vehicles that fall under that class is just the STI with the EJ257, and then WRX, FXT, and Levorg which all share the same FA20DIT engine. If there's improvement going to 100 octane on the WRX, then it follows that the FXT and Levorg will similarly benefit.

As hardwang says running higher octane is a safety net, as is running a richer air/fuel mix.

Add to that the fact that there are gas stations tested that have lower octane than advertised, meaning pumps labeled 95 will sometimes measure as low as 93, just as 97 will have 95 and it makes sense to go for 100 to have a safety net.

**Egan101** · December 6th, 2019 06:10 PM

Originally Posted by Dr.Kamiya

But you specifically said "Subaru Turbocharged Engines". I was just replying to that claim.

Right now the set of vehicles that fall under that class is just the STI with the EJ257, and then WRX, FXT, and Levorg which all share the same FA20DIT engine. If there's improvement going to 100 octane on the WRX, then it follows that the FXT and Levorg will similarly benefit.

I use either 95RON or 97RON on my FXT but I observe no difference in performance. The reason I don't use 98-100 RON on a regular basis is that I followed the advice of Motor Image on refraining on the use of such fuels as it might bring errors related to the fuel-air mixture becoming rich. I guess it would be good to use higher octane if you bring your car to the track for some fun run but on a daily basis, 95RON will do just fine.

**Dr.Kamiya** · December 7th, 2019 08:51 AM

Two ordinary cars and two sports cars on US 87 (regular fuel) vs US 91 (more or less equivalent to our 95 XCS/Vpower) vs US 93 (like our 98/100 VPower Racing/Blaze) as tested by Car and Driver:

Source: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

Even when the effect isn't measureable on the butt-dyno, a real dyno reveals actual gains. High octane = not just more power, but also better fuel economy.

**dr. d** · December 7th, 2019 08:55 AM

i haven't read it.
i am an ordinary daily driver, and just by looking at the figures, "i do not think it is worth the trouble".
which is, in my opinion, what the manufacturer had in mind all along.

**17Sphynx17** · December 7th, 2019 09:21 AM

Originally Posted by Dr.Kamiya

Two ordinary cars and two sports cars on US 87 (regular fuel) vs US 91 (more or less equivalent to our 95 XCS/Vpower) vs US 93 (like our 98/100 VPower Racing/Blaze) as tested by Car and Driver:

Source: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

Even when the effect isn't measureable on the butt-dyno, a real dyno reveals actual gains. High octane = not just more power, but also better fuel economy.

You could see that the engines mostly that did show better power and FC had the higher octane as a recommended, with the exception of the CRV (only showed minimum) and BMW in your chart.

What you are saying for PREMIUM UNLEADED only applies if it is the Recommended fuel rating as per manufacturer.

I have a car that is recommended to run on premium unleaded. The ECU can use 91ron regular unleaded but I have problems tackling inclines (parking ramps) when fully loaded. 95ron is really fine. I've also used higher 97ron in it with no benefit in FC at all.

Again, my experience is anecdotal evidence at this point but if you read the chart you showed, recommended is the way to go, not over or under.

**jut703** · December 7th, 2019 12:21 PM

Originally Posted by Dr.Kamiya

Two ordinary cars and two sports cars on US 87 (regular fuel) vs US 91 (more or less equivalent to our 95 XCS/Vpower) vs US 93 (like our 98/100 VPower Racing/Blaze) as tested by Car and Driver:

Source: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

Even when the effect isn't measureable on the butt-dyno, a real dyno reveals actual gains. High octane = not just more power, but also better fuel economy.

These are turbos and a high-displacement V8.

That same 1.5 Turbo on the CRV is on the Civic RS sold locally and there really is a slight HP bump when using higher octane fuel for it (i.e. 95 or Blaze) vs 91, moreso in the more aggresively tuned Si.

But for low-displacement naturally-aspirated econoboxes, there's no difference on the dyno.

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**hardwang** · December 7th, 2019 07:33 PM

Supposing the Blaze for example really is a cleaner fuel than any euro 4 regular unleaded. Wouldn’t that benefit the fuel filter.. and does cleaner fuel reduce carbon build up in the combustion chamber? Or is it the same?

**ferrarifan** · December 8th, 2019 08:13 AM

Originally Posted by hardwang

Supposing the Blaze for example really is a cleaner fuel than any euro 4 regular unleaded. Wouldn’t that benefit the fuel filter.. and does cleaner fuel reduce carbon build up in the combustion chamber? Or is it the same?

Premium fuels are not cleaner than their regular counterpart. What are being filtered are impurities/particulates that are present depending on how the fuel is stored and handled, not on its inherent properties, which are basically the same, except for the octane rating and amount of additives. The supposed cleaning effect of additives is for the combustion only and has nothing to do with the impurities already present.

Diesel filters do clog up faster than gasoline filters, but that's down to diesel being inherently "dirtier" than gasoline. The rate at how regular and premium diesel clogs up the filter should be the same, all other things being equal. The same is true for gasoline.

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**dr. d** · December 8th, 2019 08:18 AM

the gas innova's fuel filter is recommended by the manufacturer for regular replacement.
the manufacturer of the diesel innova, does not recommend regular fuel filter replacement.
why kaya?

**papi smith** · December 8th, 2019 08:32 AM

Same here, just looked at the figures without opening the file, the fuel economy improvement is "equalized" by the higher cost of premium gas. And if there is truth to what I heard that higher octane gas dissipates faster, then an ordinary driver like me who uses a full tank for 3 weeks, then as Doc says, it becomes negligible to me and probably a huge percentage of drivers here.