Chevy Impala

[stephenson]

Re use of premium for Audi ... is it required or recommended?

Most report regular is just fine assuming it is a modern engine with fuel/ignition management controls.

 

[MasterBlaster]

Tier one gasoline is better?

Just regular or does the blanket statement cover all grades?

What about diesel?

Can't help with diesel.

Here's the deal why Tier 1 has measurable better outcomes in many GDI engines.

The GM 3.6 engine is (gasoline) direct injection. With such (improved) engines there is no gasoline flow over the input valves. Then the exhaust gas re-circulation system sends all the crankcase vapors back through the input system to be burn't in the combustion chamber. So since there is no gasoline flow over the input valves exhaust gas recirculation crust tends to build over the input valves. Eventually this causes problems with input valve sealing and performance.

Where Tier 1 gasoline helps is that less crankcase vapors are produced and therefore less buildup on the input valves take place for GDI engines. I have seen papers that suggest that the ratio of build up on the valves is around a ten to one ratio of less build-up when using Tier 1 gasoline in GDI engines.

There's quite a bit to read online - google something like GDI engine input valve problems and read away.

 

[GrayHare]

We have to use high-test per Audi’s recommendations.

"High-test" reveals we're in the same generation. My grandfather called it ethyl.

Octane difference, sure, brand not so much IMO. Many of the no-name gasoline stations get their gas from the name brands. For those stations that do, they often also get their signage from that brand, which with a good eye one can discern.

 

[ExFlyBoy5]

I don't even know what "Tier 1" is.

It's called "Top Tier" (never heard of tier 1) and here is an article that gets into it. Basically, more detergent and Top Tier fuels may not contain metallic additives, which can harm the vehicle emission system and create pollutants. As of 2018, Top Tier Detergent Gasoline is available from 61 licensed retail brands and Top Tier Diesel Fuel is available from 5 licensed retail brands.

https://en.wikipedia.org/wiki/Top_Tier_Detergent_Gasoline

Article by Clark Howard's team: https://clark.com/cars/top-tier-fuel-detergent-gas/

As far as the Impala...I have rented several and think that GM has really upped their game in the last year or so. I am not in the market for a larger car, but if I was, it would be a top contender.

 

[kgtest]

DM had 2. The latest is much nicer than previous gen. Very inexpensive V6 option.

 

[davebarnes]

Re use of premium for Audi ... is it required or recommended?.

Audi says: required.
It is an A3 Turbo.
I really don't care about motor fuel price. We only buy 200 gallons/year.

 

[RobbieB]

Did the wiki and looks like I'm good as Chevron and Shell are on the list. Also good to not have to use premium as it can have more additives.

 

[RobbieB]

I knew I was going to get a "large car" for my first new car buy. I was considering Lincoln, Chrysler 300 and Impala. I was a bit surprised to find that the Impala is bigger than the 300.

I've got 14,000 miles on now and I'm still smiling!

 

[stephenson]

So, did quick look re Audi "requiring" premium ... can't find anyone who posted a gas filler sticker photo or from the manual - and, it may vary by year.

However, the below indicates premium in most Audi's is "recommended," not "required."

This is an ongoing debate - and, usually comes down to:
- your engine's control systems manage timing and other factors to prevent detonation
- this could, although it is another ongoing debate, cause damage, but no one has any real data
- anyone who has an Audi has the money to buy premium (an irrelevant, but nonetheless oft repeated refrain - not sure if the refrain applies to used Audis )

https://www.audiworld.com/forums/q7-mkii-discussion-211/89-octane-2931706/page7/

 

[RobbieB]

Not to mention there used to be a big difference, now it's like a dime a gallon from reg to mid and a dime from mid to high.

 

[youbet]

Did the wiki and looks like I'm good as Chevron and Shell are on the list. Also good to not have to use premium as it can have more additives.

Pretty extensive list. Even the common truck stop brands (convenient for us when towing the camper) are there.

I was a bit surprised that nothing related to Walmart, Sam's Club or Member's Mark was on the list. We have a Sam's Club station nearby that is consistently the least expensive place to fuel up, but they don't appear to be on the Top Tier list. I wouldn't want my 21 year old, high mileage F-150 to have it's life cut short because I'm buying crappy fuel!

 

[stephenson]

More like $0.40 a gallon difference where I live - regular to premium.

 

[jazz4cash]

Not to mention there used to be a big difference, now it's like a dime a gallon from reg to mid and a dime from mid to high.

Just the opposite around here. The shell station I use right now has
Reg 2.49
Mid 3.09
Prem 3.29

That’s 80 cents per gallon extra for premium and this particular station generally has the cheapest gas for miles around (except for the independents). I used to know guys who used premium even if it wasn’t recommended......not anymore!

 

[Andre1969]

Where are y'all finding 10 cent/gal increments for 87/89/93? I haven't seen that around 1999, just before fuel prices started rising toward the end of the year. After that, it seemed like once prices started coming back down to reasonable levels, they started really jacking up the increments.

I have a 2012 Ram Hemi that calls for 89. The gas station I usually go to, a High's, usually has fairly even increments. Say, $2.49/$2.79/$3.09. Sometimes the 89 might be a bit closer to 93. But, there have been times that the 89 was so high-priced, and if the tank was low enough, I could fill up with half 87, half 93, and save 5 or 6 bucks, versus using 89!

 

[NanaW]

I loved our Chevy Impala 2011 but I just retired and we no longer had a use for it, so we sold it and bought a TT instead

 

[stephenson]

Sold Impala and got a TT!

Schweet!

 

[jazz4cash]

According to gas buddy, I see in CA the premium is about .10 /gal more than here in MD and the .10 increments apply to mid-grade and regular.

 

[GrayHare]

But, there have been times that the 89 was so high-priced, and if the tank was low enough, I could fill up with half 87, half 93, and save 5 or 6 bucks, versus using 89!

Note that mixing octane grades does not yield the average octane equivalent. An octane rating expresses a resistance to ignition, higher octane is less likely to ignite prematurely. Mixing low octane into high octane gas causes that high octane gas to ignite much sooner than the average of the two grades. Half 87 and half 93 might ignite something like octane 87.5.

 

[shortstop14]

My first car in high school and into college was a '62 Impala. Bought for $150 and sold for $150. Wish I'd have kept it, but it was pretty beat up by 1976.

 

[PartIrish]

My first car was a 1965 Impala standard transmission ("3 in the tree") inherited from my older sister. No radio, no AC, so long drives involved singing at the top of our lungs for entertainment. I had to let it go when gas hit $1.00/gal in 1980 and the car got maybe 10-11 MPG. We named her 'Alberta the Big German Girl' for reasons I don't remember, haha.

 

[Ronstar]

My first car was a 67 impala. Great car. 150k miles in 1974, so I traded it for a nova. Got $150 for the impala. Should have kept it. Even though it had been in a few wrecks, had some rust, and only ran on 7 cylinders after I broke off a spark plug. And I used to be able to start it without a key.

 

[GrayHare]

Dave's 1972 Impala with 450,000 miles still runs. http://www.stillruns.com/

 

[Andre1969]

Note that mixing octane grades does not yield the average octane equivalent. An octane rating expresses a resistance to ignition, higher octane is less likely to ignite prematurely. Mixing low octane into high octane gas causes that high octane gas to ignite much sooner than the average of the two grades. Half 87 and half 93 might ignite something like octane 87.5.

But, that's how the gas stations do it. There is no 89 octane that's actually formulated. They simply draw gasoline from the 87 octane tank and the 93, and blend it to make 89. I learned this years ago, when the local station ran out of 87 and said they're only selling 93. So I asked, what about 89, and they said that it was a blend, so when the 87 ran out, so did the 89.

Unless, the mixing process the gas stations use is more complicated than that?

 

[jazz4cash]

But, that's how the gas stations do it. There is no 89 octane that's actually formulated. They simply draw gasoline from the 87 octane tank and the 93, and blend it to make 89. I learned this years ago, when the local station ran out of 87 and said they're only selling 93. So I asked, what about 89, and they said that it was a blend, so when the 87 ran out, so did the 89.



Unless, the mixing process the gas stations use is more complicated than that?

GrayHare’s post was a surprise to me. I’d like to see some documentation for that comment. Remember years ago Sunoco gas stations offered about 5 different octane levels which was a blend of their economy and premium grades?

Here is a link to a Sunoco webpage that validates the final octane of mixing two grades is just a volume weighted average.

https://www.sunocoracefuels.com/tech-article/mixing-fuels-calculating-octane

 

[GrayHare]

Blending can work to lower octane, but the ratio is important. To change 93 octane into 89 octane perhaps you add 10% of 87. I don't know the proper ratio, but the concept I learned in high school chemistry.