What kind of gasoline do you use?

When I first got my XJ it ran okay, but it buzzed at certain rpm's. I remembered being told that in 1981 regular gas had a higher octane rating than it does today, so you should use mid-grade gas in older vehicles. I tried it, and lo and behold my bike does run smoother and with more power on mid-grade. I've also heard that premium may be too much octane for most older bikes. Any thoughts?

 

I use the highest octane that the pump has.

 

I've been running 89.

 

High Test.
I'm getting better performance with it.
The Regular was making a sound I'm sure would lead to trouble.

I'm treating this Old XJ to the Good Stuff.
Just like I did with my new MGB, back in '72 ... when Sunoco had that 260!

 

high octane

 

I read that the higher octane gas may not be the best though because it is older than regular. Most cagers don't put premium in their cars and therefore it sits in the storage tanks longer whereas the regular gets turned over much more.

What are your thoughts to this?

 

I think it all comes out of one tank, anyway ... the higher octane rating is baloney and steeper price just makes you feel more important!

 

The highest octain I can find. Around here that is 89. Gets better performanc as well as better mileage.

 

I run the highest also, treat my baby good. It is 93 here. Never tried anything else.

 

I have heard that the gas comes from the same tank, but at different levels, not sure if top or bottom in the tank is higher octane though. I only use the high octane in mine, lately with seafoam additive to clean it some more.

 

I just had to throw my 2 cents in here!Contrary to popular belief/myth higher octane fuel doesn't come out of the same tanks but it can dissapate a small amount when sitting in the tanks but doesn't lose any octane! I work in the fuel business and I get asked this quite often. Also my 1980 XJ 650 runs nicer on high octane and way better mileage too.But being a cheapskate I often put the cheaps stuff in and then kick myself after(lol)
Hope this helps a bit!

 

I put in 89. My bike runs like crap on 87, but I don't see any real difference between 89 and 93 so I stick with 89.

 

87. I can try some other flavors, and I have in the past, but I'm not sure I noticed much of any difference.

 

I use premium, which is 93 octane. I've been back and forth all summer between 87 and 93. Mileage-wise not much difference but performance wise it sounds and runs a bit better on premium. I buy about 2.5 gallons a week so the price difference is barely noticed.

 

premium,,I try to stick to the name brands,,,,I don't buy the agument it's all the same.
an yes I remember sunoco 260,,,,an still buy sunoco alot but I've been on a Marathon kick latly because I heard they don't buy mideast oil
an I once owned a 69 MG miget,,,1275cc 4 cylnder motor it was a motorcycle with 4 wheels type fun nothing but premium an loved to run with your foot flat on the floor,,,,,of course everything I drove love to run flat footed back then...I weighed 120 lbs back then I don't think I could fit in 1 one now at least not comfortable,,,,but that car was fun in the turns

 

I run only 87 octane regular in my Seca, and she runs great. The factory manual calls for regular, and that's what she gets.
One of the most informative pages on octane ratings can be ound here:
http://www.faqs.org/faqs/autos/gasoline-faq/part3/

Be sure to check out the section on using mothballs as an octane booster!

 

87
but give her a bit of 89 when shes a dirty girl(wink wink)
mild differance, but benifit is arguable.
depends if i have the extra .50 to use the better stuff

 

I read the section on Mothballs. It seemed to say that to use them to increase octane in your tank also leaves residue as it needs to burn up at such a high temperature. Sounds like I will be leaving that alone as I have no experience tearing my carbs apart, and don't wish to learn until I have some space and a bench to do them on. Dispather, Have you used mothballs before in your bike?

 

I'm so impressed I actually know something about this. We build gas stations all the time, so here is what I know.

There are two unleaded tanks at most gas stations. Here we have our choice of 87, 89 or 91 octane ratings. The one tank holds the 87 and the other holds the 91. They mix in a valve to create the 89 octane.

As I far as I know about all this, high compression is needed to get the most out of high octane fuels. I run jet ski's a bunch and know that if you don't have a high compression head you are just waisting your money. most people only notice a change when they move 1 grade up from normal, but most people don't see high enough compression to notice any change beyond that. I currently own a subaru turbo car that requires 91 at the pump. I notice a huge difference in the power and sound of the engine when I use something less. 89 is okay, but you get down to 87 or even 85 it is just crap. These bikes don't have the compression to require 91 octane gas. You may just be waiting your money, or at least that's what I've been told.

 

I use 91 here, the highest I can get. Mostly because the mid grade has 10% ethanol, and I accidentally pushed that button once, and it made my yammy run like garbage. I won't even bother with the normal 87 stuff. I used to have a carbed car, and whenever I put the stuff with ethanol in it, it ran like garbage too.