higher octane gas?

[Philip2]

Have a 2015 3.8 G80. The dealer says that the engine is tuned for 87 and using higher octane will make no difference.
A friend says premium will give me 7 more horsepower, which is no big deal anyway.
Is there any benefit to using higher octane gas in terms of of engine wear or performance?

 

[EdP]

Have a 2015 3.8 G80. The dealer says that the engine is tuned for 87 and using higher octane will make no difference.
A friend says premium will give me 7 more horsepower, which is no big deal anyway.
Is there any benefit to using higher octane gas in terms of of engine wear or performance?

The main advantage to using higher octane fuel with that engine is more profit for the oil company.

You will find is discussed here in other threads and a couple of people said they felt minor differences, most said no difference. Best to use a Top Tier gas though. Most name brands are in that category with the additives.

Not convinced? Try a tank for the extra 10 bucks and see if there is a difference. I'd rather invest that money in a good steak on the grill.

 

[MorrisGray]

We have always used 87 octane in our 2012 H/Genesis with the 3.8L v6 naturally aspirated engine and had no problems with knock or performance. Using regular grade gas is like a real benefit that you can put in your pocket. All of the competition and even optional engines that have turbo assisted motors are requiring or suggested to use premium grade gasoline. That is a negative for me. Many people from what I have read about are even using regular 87 octane in their cars that are suggested to use premium grade. I have been shopping for what I want to buy next and Lexus GS350 is on my list, one example of my statement even though their v6 is also naturally aspirated it is suggested to use premium. Now the Lexus ES350 only requires 87 octane regular, even though it has the same basic motor with 302hp/267lbft torque 11.8:1 compression vs the GS350 311hp/280lbft - 11.8:1 ...... Numbers are very close, probably same engine, same compression ratio given, why one is said to require premium is beyond me unless it makes people think differently about their car?

 

[Ragnar]

Ya hit. The nail on the head Ed,for years it’s been a known fact that unless it’s listed by the manufacturer that using 91 octane fuel is just a plain waste of money! 87 octane is all most of today’s engines need.Strange how some folks insist that using the higher octane fuel gives them better gas mileage and or more hp. There are those engines that need 91 it will be listed right on the window sticker.
My thought is if ya wanna continue to piss your hard earned money away knock yourself out.

 

[PMCErnie]

We have always used 87 octane in our 2012 H/Genesis with the 3.8L v6 naturally aspirated engine and had no problems with knock or performance. Using regular grade gas is like a real benefit that you can put in your pocket. All of the competition and even optional engines that have turbo assisted motors are requiring or suggested to use premium grade gasoline. That is a negative for me. Many people from what I have read about are even using regular 87 octane in their cars that are suggested to use premium grade. I have been shopping for what I want to buy next and Lexus GS350 is on my list, one example of my statement even though their v6 is also naturally aspirated it is suggested to use premium. Now the Lexus ES350 only requires 87 octane regular, even though it has the same basic motor with 302hp/267lbft torque 11.8:1 compression vs the GS350 311hp/280lbft - 11.8:1 ...... Numbers are very close, probably same engine, same compression ratio given, why one is said to require premium is beyond me unless it makes people think differently about their car?

Agreed! I use only Top Tier 87 in my ‘12 3.8 and it’s great!

Just a minor point. The GDI engine is hardly a “naturally aspirated” engine. It’s a direct fuel injected engine, a big step up from the olden days of carburetors and even the early fuel injected engines.

 

[glennk]

Unless the manufacturer has stressed 91 or 93 OCTANE REQUIRED in the manual or fuel filler door, I'd stick to 87. Performance loss is minimal at best.

 

[pmckechnie]

First of all, I have never tried 93 oct gas in my 2018 3.8 because the gain would not be enough to offset the price.
Modern computer controlled engines are tuned to run with the gas they have to work with. Emissions are number one concern. MPG is second and power third. A lot of the decisions are made by the accounting and sales departments. They decide if 311 hp or 318 hp will bring in more customers or if 27 mpg or 29 mpg will bring in more. The engines and computers are the same. If they decide that being able to say the car runs on 87 oct gas which will be cheaper to drive, then 87 is recommended. If they decide that 318 hp and 29 mpg is a better for sales then 93 oct is recommended.
So the final decision is up to you, the owner.
I don't know if the above figures are exact, but the logic is correct.
I chose to use 87 oct. I want lower cost per mile.

 

[REMIX]

My 5.0 seems to run smoother with premium. Maybe it's just me.

 

[MorrisGray]

PM... That really makes a lot of sense! I thought that surely Lexus would use the same engine in the GS350 as the ES350 and yet they show different hp and torque ratings for the two and to use 87 octane in the ES but use 91 octane in the GS. Now from your explanation, it makes sense. Also on the Lexus forums there are some owners that say they use regular 87 octane in their GS350 and have no problems. Again from your explanation that would make sense.
I am pretty sure that Honda and Mazda both state that you can use premium or regular in their new 4cyl turbo engines and obtain around 250hp with premium and 225hp with regular. Not sure on the exact number but close.

 

[1FstYota]

It's about knock detection, the higher oct has higher knock threshold and the ECU can detect this when you run 87 oct the depending on the knock count, it can retard timing and thus loose HP, you reason you feel its the car is smoother is cause with higher oct the ecu advances the timing abit more to give you back what you lose with lower oct gas.

It won't do crap for performance besides getting that little bit of HP back. Unless you raise the compression or add a turbo or two don't expect miracles. this of course is more noticeable in forced induction setups.

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[carguy75]

My 5.0 seems to run smoother with premium. Maybe it's just me.

So true, my 2015 5.0 ran like crap(rough idle and felt slower) with 87 octane compared to how it runs with 93 octane. I am sure the 3.8 will runs better with 93 octane as well.

 

[1FstYota]

So true, my 2015 5.0 ran like crap(rough idle and felt slower) with 87 octane compared to how it runs with 93 octane. I am sure the 3.8 will runs better with 93 octane as well.

3.8 feels a bit peppier on 92oct. of course you will have to run a few tanks first if all you did was 87.

 

[Ragnar]

Been running our 2016 3.8 Ultimate on sams club 87 octane fuel since we bought it in early ‘16 and she’s running just fine.

 

[robthoke]

I've got a 2015 3.8 AWD and have always used 87 octane. Top tier gas however gets me better mileage on those highway trips.

 

[Gen127]

Top Tier 91 octane almost exclusively on my v8.

 

[cubanben]

In my 2015 3.8 the first tank full was 87 octane regular (Shell). The following day, the engine began vibrating violently, the car was jerking back and forth, every light imaginable lite up on the dash. I had to pull over and shut down the car. I restarted and everything ran fine. The only remaining issue was the check engine light remained on. Oh great I thought. I just bought this car and three days in I have a problem. Two days later the check engine light turned off. On my next refill, I went with 93 octane (BP preferably & Shell) and I've never looked back.

I've never noticed performance difference in the octanes, but I've normally used 93 octane on my vehicles in the past. Lucky (unlucky actually) for me I barely drive since I use public transportation during the week; so I only fill-up once every 4 to 6 weeks (I have less that 10K miles). Higher octane fuels burn cleaner and therefore leave fewer deposits giving better, overall performance.

Anyway, that's my 2 cents. Enjoy your rides.

 

[EdP]

In my 2015 3.8 the first tank full was 87 octane regular (Shell). The following day, the engine began vibrating violently, the car was jerking back and forth, every light imaginable lite up on the dash. I had to pull over and shut down the car. I restarted and everything ran fine. The only remaining issue was the check engine light remained on. Oh great I thought. I just bought this car and three days in I have a problem. Two days later the check engine light turned off. On my next refill, I went with 93 octane (BP preferably & Shell) and I've never looked back.

Anyway, that's my 2 cents. Enjoy your rides.

Actually a lot more than your 2 cents. Quite an upcharge for the 93 octane. I've been tempted a couple of times but never bothered. I have over 50,000 miles on two different 3.8 engines with not a problem. That is about 2000 gallons over 3 years. The difference is considerable and can be put to better use IMO, but, your money, your choice.

 

[Mcc]

Actually a lot more than your 2 cents. Quite an upcharge for the 93 octane. I've been tempted a couple of times but never bothered. I have over 50,000 miles on two different 3.8 engines with not a problem. That is about 2000 gallons over 3 years. The difference is considerable and can be put to better use IMO, but, your money, your choice.

You never miss something you never had. I am sure it runs fine with regular but you would have to try a month or maybe 6 tankfulls with premium and under different conditions and driving styles to really tell if it makes a difference. This is assuming premium is recommended.

 

[EdP]

You never miss something you never had. I am sure it runs fine with regular but you would have to try a month or maybe 6 tankfulls with premium and under different conditions and driving styles to really tell if it makes a difference. This is assuming premium is recommended.

If recommended I would use it or at least try it and decide. The 3.8 is designed to run on 87 octane. A few people have said there was minor difference. others said none. I doubt the problem cubanben had was related to the octane of his fuel.

 

[Mcc]

I agree. Sorry, I misaimed my response. I probably should have replied to someone who had an engine where premium was recommended.