@texases any idea, then, why that was a popular recommendation “back in the day”???
I was always puzzled by the admonition because the owner’s manuals of those previous cars never included such a recommendation.
Back in the day, many of those mechanics OWNED the local gas station and would be more than pleased if you cheapskates would run a tank of premium through 'cause they’ve got a boat payment due! 
I am going to partially agree with texases.
Even though the added octane of a premium gas wouldn’t have helped a car that only calls for 87 octane, years ago many gasoline companies put higher levels of detergents in their premium-grade gas, so in some cases that premium gas might have helped to clean the carb or the injectors to some extent.
However, in this day and age, the idea of premium gas providing some sort of advantage for a car that only requires “regular” gas is…bogus.
Ah, I had forgotten that years ago premium gas had detergents added not in regular grade. That rings a memory bell now…yep, the “cleaning” action was the reason given me at the time and why I was told to run a full tank of the premium grade through and not just a partial tank amount added to, and diluted by, the regular grade normally in the car’s tank. Thanks for the explanation and for reviving a forgotten memory.
It’s true that some premium gas had/has more detergent, so there was a slight benefit to doing it. But the vast majority of cars never saw any premium, and I don’t think they suffered for it.
@texases – I think I may have run premium maybe a half dozen times through the '87 Olds but never have bothered to on the '07 Impala and definitely not on the 2014 Camry. Don’t recall about the '73 Corolla. Never noticed any beneficial difference the few times I did.
EDIT: I did run premium when driving at high elevation through mountains and high desert areas out west on extended driving trips in 1990 and 1991 to avoid engine pinging and loss of power since everything was set for my normal lower elevation.
“I did run premium when driving at high elevation through mountains and high desert areas out west on extended driving trips in 1990 and 1991 to avoid engine pinging and loss of power since everything was set for my normal lower elevation.”
Actually, Marnet, somebody gave you bad advice.
At high elevations, your engine requires a lower octane than at sea level !
feeling thunderstruck Well for pity’s sake…now I find out. Sigh.
I think a lot of people assumed that high octane gas also contains more detergents to keep the fuel system and intake tract clean which was the basis for running premium through the car “several times a year”.
Whether or not premium actually does have more detergents, I don’t know.
On the other hand and in Marnet’s case, a higher octane could have been beneficial due to the engine having a distributor and anyone’s guess about what the ignition timing was set at and/or how any of the ignition timing controls were operating.
The latter part of that meaning an assortment of thermovalves, time delay modules, etc, etc.
@ok4450 Gotta admit that’s all Greek to me. LOL. It was the GM 3.8L engine with four speed transmission in the '87 Ciera. Still miss the low end torque, acceleration and smoothness of that machine. Most comfortable, enjoyable car I’ve owned to date.
One of the things that makes Top Tier gas is that to be labeled as such. the regular must have the same level of detergents as premium. Obviously gas that isn’t labeled Top Tier doesn’t meet these requirements.
You seem to set a lot of store in the fact that timing is retarded under load even using premium.
Of course timing is retarded under load when you have a knock sensor. Running more advance under light load gives better fuel economy and the knock sensor lets you do that.
You say that the timing is retarded 8-10 degrees more on regular, how do you know that is enough to prevent damage? I didn’t see that you got data from 100% load.
You also said your mileage didn’t suffer but you didn’t provide any data.
Dis you test with 86 octane or even 85 ? These are sold as regular at high altitude and manufacturers have to guard against against drives filling up with them and then returning to sea level.
There are safety margins built into many products, I just don’t think it is wise to push them without good reason.
I’m reviving this thread but with a new twist on the subject of…“can regular grade gasoline be used safely in a premium fuel required car?” I understand the loss of performance, and the possibility of engine damage if regular grade gasoline is used during heavy engine load.
Now the new twist… Do modern engines with computers (my car is a 2015 Mercedes S-550) actually track the amount of time the timing is retarded when using regular grade? And, will the manufacturer withdraw their warranty because regular grade gasoline has been used excessively…even though there has been no engine damage?
Please don’t flame me for having a high $$ car and unwilling to buy gas for it. That is not the case… I just want your interpretation of what the computer is capable of documenting and the position car manufacturers would likely take under the scenario of driving such a car with regular gasoline.
If I followed through with using regular (say 87 octane vs 91 octane required) and took my car in for regular maintenance (no engine problems) at which point the dealer could download the computer and observe predominant use of regular grade fuel…what would be the dealer’s reaction?? Could the dealer void the warranty??
Manufacture says (required) use premium fuel. End of discussion.
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It is very easy for any manufacturer to program their computer to collect and save retard and advance behavior data. I don’t know if they do it or not, or if they’ll begin doing it the next time your car’s software gets upgraded for some unrelated reason. My point is it’s trivial for them to do this.
However, and I’m not a lawyer, how could they prove what kind of gas you are buying? You could think you’re buying premium from your local corner garage, but instead they dilute their premium, or use some inferior premium. Would that be grounds to void a warranty?
Why are you even asking this question in the first place?
Is it possible . . . if you were to get information, which would lead you to believe there are no consequences to using 87 octane, you would go ahead and do so, especially if you felt the manufacturer couldn’t prove you used fuel with an insufficient octane rating for your vehicle?
Yes, I tend to see things negatively
That said . . . in my experience people don’t ask your question, if they weren’t at least entertaining the idea of using 87 octane in their car which requires premium
I doubt any manufacturer would do that and if they did it would hold up in court.
Using lower grade gas then engine is designed for is not the only thing that can cause an engine to knock. So it would be impossible to tell what is causing the engine knock. Thus the legal problem.
But I agree. WHY. Makes no sense for someone to by a $60k plus vehicle and then run the risk of engine damage and less performance. Remember that less performance also equates to worse mpg. So you’re not saving anything.
Define “reasonable circumstances.”
I drive the same generation of TL as you’re talking about. It’s decently fast, and I use that capability when merging on interstates or turning onto a highway from a side street. Sometimes I have to floor it to avoid being rear-ended by the idiot behind me who is too busy texting people to look at the road.
All of those scenarios will put high loads on the engine - and the last is especially bad because even assuming I decided to “put light loads” on the engine, I now have to choose between causing predetonation and getting the back half of my car crunched.
This, I think, is the much more reasonable approach. We wear seat belts because unforeseen circumstances might arise that result in their necessity. Many of us will own a car until it rusts out around us and never need the seat belt because we won’t ever get into a wreck. This is not an argument to eliminate seat belts from vehicles.
And regarding the gas, all of this hand wringing comes over a 40 cent per gallon difference in price. On my average fillup, this means I spend an extra 4 bucks. As I fill up on average once every two weeks, this costs me a whopping 96 bucks a year.
I spend more than that on my morning coffee. I spend a lot more than that stocking my liquor cabinet. Hell, I probably spend more than that per year on chewing gum. If I keep the car 20 years it’ll cost me an extra $1900. Meanwhile, replacing the engine will cost more than that just to get the engine. Then I gotta either take the time to install it myself or pay a guy to do it for even more money.
Putting in the required grade of gasoline is simply a cheap insurance policy against damage.
Or to put it another way, and something that’s been said time and again, if you want to use cheap gas, make sure you buy a car that calls for cheap gas. Why would you spend $40,000 on a luxury car and then be upset at less than $100 per year? Spend $30,000 on the Honda version and you can use all the regular gas you want, and save $10,000.
Specifically regarding the Acura TL, I’ve had mine for 10 years now. I’ve therefore spent an extra $950 or so in gas. Unlike most luxury cars, the Honda underpinnings mean actually maintaining the thing has been absurdly cheap. I’ve put in less than $2,000 in non-oil-change maintenance and repairs over the life of the car. Similarly-equipped BMWs can cost that much in a year (and also require premium). Given the ridiculously low cost of maintenance on this thing, I really don’t see much to gripe about in the extra gas costs.
I agree with you, but the forum member didn’t want to be told that…
I’m still trying to figure out why you are asking your question if–as you claim–you have no intention of running the car on regular. There are a lot of theoretically problematic situations in everyday life, but why would you worry about them if you have no intention of becoming involved in something that could…theoretically…cause problems for you?
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I remember being on a spaceflight forum many years ago, and some nitwit posted something along the lines of “We obviously didn’t go to the Moon. If we did, prove it, but you aren’t allowed to use NASA footage or documentation at all.”
No! Not an option! I’ll answer however I want, and artificially constraining my answer with narrow parameters designed to funnel me into their whackjob conspiracy narrative ain’t happening, bud!
No matter the topic I may be discussing on a forum, from cars to politics to Star Trek, I refuse to pay attention when OPs tell me what I am and am not allowed to say. If OP didn’t want people to fuss at him about splurging on an overpriced car vs. being a cheap little miser at the gas pump, then he shouldn’t have posted the topic. If I ask a question, I have no right to expect that people should feel obligated to only give me the answer that I tell them I want to read.
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