Howdy everyone! On my last three fills I've used mid-grade gas on my nearly new 2.5l Golf. For whatever reason, I've noticed the car gets slightly better gas mileage and the engine seems to run stronger. Question: Is the gas from the two service station tanks (reg/premium) despensed equally? If so, I'm assuming the premium tank does not get refilled as often as the reg. tank? Any possible neg. issues? On the positive side, if using high quality gas like Shell (w/more cleaning additives in their premium gas), I would think this would be a good for the fuel injectors? The engine/car calls for 87 oct. gas. Can you see any long term effects besides costing more $$? Thanks for any and all replies!
Mid-Grade Gas
- Thread starter sparky123
- Start date
- Status
No, no affect at all.
Did you buy it used? If it's running better with higher octane than recommended chances are there could be some carbon build up on top of the pistons or they added a computer program to use higher octane. Higher octane does nothing for me.
To answer your first question, the owner of a local Shell Service station told me he has two tanks and that the mid-grade is drawn from both tanks, mixed at the pump. He knows I rarely buy his gas (way too expensive) and has been a great resource for my cars over the past 10 years, so I've no reason to think he's lying to me.
If octane is too low and detonation starts to occur the knock sensors reel in timing. You may never hear the spark knock because the timing is retarded almost instantly. Little higher octane and timing is advanced. Little more zip,little better fuel mileage.
Last edited:
some engines do run better on higher octane.
as they pull timing if they detect knock on 87.
for example one of the new ford cars(focus?) hp rating was achieved on 93 octane. but they only require 87.
FWIW I never noticed a difference without a tune for premium fuel.
That being said my subaru seems more peppy with super(93) but I get no mpg bonus so I rarely use it.
as they pull timing if they detect knock on 87.
for example one of the new ford cars(focus?) hp rating was achieved on 93 octane. but they only require 87.
FWIW I never noticed a difference without a tune for premium fuel.
That being said my subaru seems more peppy with super(93) but I get no mpg bonus so I rarely use it.
Last edited:
Some engine run slightly less well on premium when regular is recommended. This from a C&D test, with DATA.
Here in Nebraska the cheapest gas is 89 octane with 10% ethanol, mid-grade (price-wise) is 87 octane (no ethanol), and premium is 91 octane. I seem to get the best mileage on the 87.
Placebo.. If the car specs regular, use regular.
Originally Posted By: ag_ghost
To answer your first question, the owner of a local Shell Service station told me he has two tanks and that the mid-grade is drawn from both tanks, mixed at the pump. He knows I rarely buy his gas (way too expensive) and has been a great resource for my cars over the past 10 years, so I've no reason to think he's lying to me.
correct. this is how it's done @ 99.9% of stations.
2 grades in the big tanks, Reg& Premium,they get mixed @ the dispenser to make the mid grade.
To answer your first question, the owner of a local Shell Service station told me he has two tanks and that the mid-grade is drawn from both tanks, mixed at the pump. He knows I rarely buy his gas (way too expensive) and has been a great resource for my cars over the past 10 years, so I've no reason to think he's lying to me.
correct. this is how it's done @ 99.9% of stations.
2 grades in the big tanks, Reg& Premium,they get mixed @ the dispenser to make the mid grade.
Last edited:
Originally Posted By: SLCraig
Placebo.. If the car specs regular, use regular.
+1. Running anything beyond what the car calls for is pointless. The MPG you gained is purely coincidental. Do some long term testing, one tank regular, another midgrade, back and forth several times with carefully logged data.
Guaranteed your margin for error more then exceeds whatever gains you think you're getting.
Also all fuel has plenty of additive. Its doing nothing for your injectors.
Placebo.. If the car specs regular, use regular.
+1. Running anything beyond what the car calls for is pointless. The MPG you gained is purely coincidental. Do some long term testing, one tank regular, another midgrade, back and forth several times with carefully logged data.
Guaranteed your margin for error more then exceeds whatever gains you think you're getting.
Also all fuel has plenty of additive. Its doing nothing for your injectors.
I'm sure it calls for minimum 87 octane. I use the 89 for exactly the reasons you mentioned. Since I've been using it, I've had far less (Pretty much none anymore) pinging under hard uphill acceleration. That alone is worth it to me.
Funny that my mom's 96 toyota corolla runs better on 93 than on 87. Wouldn't believe unless I hadn't seen it with my on eyes. Idle rough on 87 and smooths out on 93 and it's very noticeable.Not the engine you would expect that to happen to. My buick doesn't know the difference. My camry, I haven't tested yet. But it is of interest to me that in my camry manual it mentions that test results are based on using 91 octane.
A dealer told me once that the mid-grade mix was 10% premium, 90% regular. Don't know if this is true or not.
It is possible that MPG and power slightly increase. It depends on tune from the factory.
I have a vehicle(Acura 3.7 V6) that requires premium and honestly when regular was put in notice very little difference running it. The MPG did drop a full 2MPG on the tank which is huge considering 19-20MPG is normal. Hardly worth the "savings" since premium is only costs about 5-6% more than regular fuel.
Mid-grade is definitely a blend of premium and regular. Octane is linear so if you put half a tank of 87 and half a tank of 93 it makes 90 octane.
My wife plays games putting in mid grade into her Subaru turbo requiring 91 octane if the tank has at least 50% 93 octane in it. The next fillup she puts premium in again and then midgade etc.
I have a vehicle(Acura 3.7 V6) that requires premium and honestly when regular was put in notice very little difference running it. The MPG did drop a full 2MPG on the tank which is huge considering 19-20MPG is normal. Hardly worth the "savings" since premium is only costs about 5-6% more than regular fuel.
Mid-grade is definitely a blend of premium and regular. Octane is linear so if you put half a tank of 87 and half a tank of 93 it makes 90 octane.
My wife plays games putting in mid grade into her Subaru turbo requiring 91 octane if the tank has at least 50% 93 octane in it. The next fillup she puts premium in again and then midgade etc.
They size the tanks appropriately so fuel doesn't go stale. If you look at some pumps there's a small odometer thing, rather two of them, for gallons dispensed over the lifetime of the setup. Two "odometers" means mixing midgrade. You can also get a feel for how much premium any particular station sells from these gallon meters.
Don't let anyone on the internet tell you your specific car will run better/ more economically with or without a boost. Do your own study, preferably double blind with someone else buying the fuel for a while.
Don't let anyone on the internet tell you your specific car will run better/ more economically with or without a boost. Do your own study, preferably double blind with someone else buying the fuel for a while.
Another reason to use my scan tool. See if you timing changes between grades. Power and fuel wise I don't feel a difference.
Always use as little octane as needed.
In your case, you need a bit more, for whatever reason.
An option is to mix your own - pump 87 and 91-93 together.
You could tailor it perfectly, an maybe also save a bit of $.
In your case, you need a bit more, for whatever reason.
An option is to mix your own - pump 87 and 91-93 together.
You could tailor it perfectly, an maybe also save a bit of $.
Originally Posted By: sparky123
On my last three fills I've used mid-grade gas on my nearly new 2.5l Golf. For whatever reason, I've noticed the car gets slightly better gas mileage
Originally Posted By: sparky123
I bought the car new about 6mo ago. thanks.
Maybe your motor finally broke in.
On my last three fills I've used mid-grade gas on my nearly new 2.5l Golf. For whatever reason, I've noticed the car gets slightly better gas mileage
Originally Posted By: sparky123
I bought the car new about 6mo ago. thanks.
Maybe your motor finally broke in.
- Status
Similar threads
- Locked