I drive a Toyota so am used to using cheapest gas I can find.

So, today I put in about 10 gallons of 87 octane. Car had probably 2-3 gallons of 91 in it already.

When I realized my mistake, I added another 3-4 gallons of 91 octane.

Have driven it about 30 miles w/o any hiccups.

So, if it starts behaving badly should I add octane booster, drain gas, continue to add more 91 as she drives it, or simply live with it???

Also, would the car have acted up by now, after driving 30 miles?

Thanks

 

You should be fine.

 

I've driven my XJ8 on 87 for years, runs great.

 

This has been quite a can of worms before, with opinions all around.

I don't think that there is anyone who will say that this one incident will cause any sort of damage. Some people use the lower grade regularly, and say that there is no problem, while others say that there is. So it goes.

Personally, I figure that the engineers who designed and built the car know more about it than anyone else, so I figure I will adhere to their recommendations. Surely, this one incident will not damage your car.

 

Three-four years ago there was a multi-week shortage of anything other than 87 octane in the Atlanta area. I had always used 91 but that was not an option. Car ran fine, mpg did not change, perceived power did not change. Nothing changed. Research indicated that the knock sensors would handle most pinging issues with timing advance retard.

Bottom line is that to reach the advertised HP of the AJ27 engine you need 91 octane. For everyday casual driving 87 octane is fine.

Been using 87 ever since.

 

Bingo.

Being that the only difference between regular (87) and premium (91) is the octane rating, and the knock sensor will kick in long before any damage is done, the only possible outcome would be slightly reduced performance and increased fuel consumption.

I frequently switch from 87 to 91 depending on local pricing and the health of my stock portfolio and in all honesty notice NO difference.

 

I use 89 consistently because it is the only grade available as ethanol free, and never experience issues. Most, but not all octane boosters use alcohol as an octane booster, so beware if you do use an additive, but I would not personally be concerned about what you have done and would just burn through it.

 

Howdy Folks:
Maybe someone will do a poll.
I have been running 87 octane in my 2002 JAGUAR XKR for nearly 3 years with no problems which include 10,000mi in road trips from Canada to Key West. Just my 2 cents.

 

there are 2 times I would be staying with premiium, you live in a Mountainous region which meens you drive under higher engine loads up grades. and 2 youre supercharged. otherwise I know many customers that run 87 without issue or loss of mpg or power.
Have an R and run 87 youll be fine if youre never into boost, but then why did you buy an R to drive like a grandma? Otherwise run premium, it only takes once on a supercharged engine to quickly cause damage. KNock sensors controling timing to ward off engine damaging knock yes, BUT theyre KNOCK SENSORS, which meens the engine is KNOCKING for them to sense and then retard timing. Like trying to get your seat belt on as you are getting into a accident

 

...with this twin screw, I think that I'm stuck with the expensive stuff. Hah!

What Brutal wrote rings true.

 

Absolutely!!! Most people do not understand this. Even though you might not hear the Knocking itself, the computer is continually responding to the detonation by retarding, and then slowly advancing, the timing until it detects detonation again.

 

No one has said anything about emissions sensors. Maybe the jag is not that sensitive? I experimented with 87 in my VW Touareg several years ago and got a check engine light part-way through the tank. I refilled with high octane and it went away. I was told that it triggered an emissions sensor.

 

My wife always buys premium. It's her car, the owners manual says "run premium gas", so she does....

Whenever I have to fill it up for her, I buy regular. I know the engine will run just fine, but I never tell her that I've put regular in it. I don't need yet another hassle from her....

As always, her XK8 runs great....

 

I will always buy the 91 (or higher when available). In your case I would fill the tank with the correct fuel before or after each drive until you're confident the 87 has been purged or consumed... 00.02c

 

once i supercharged mine i never run anything but 93. I didnt put over 10k in the engine to try and save $4-5 a tank

 

Any significant reduction in timing advance would be accompanied by a loss of power and increased rate of fuel consumption. If neither of these are actually experienced when operating on regular octane gas, what does that suggest?

 

Going forward I will run 87 in my XJ8 and 91 or 93 in my XJR.

 

ok for XK8 but not XKR

 

Interesting

 

With my luck, the engine would explode.

So for $3 more a tank, I'll try to remember to use 91 octane.