What kind of gas do you run?

I usually buy either "premium" or "ultimate", and I always put a splash of lead substitute in with a full tank. I guess I'm just wondering if it's worthwhile to spend the little extra for better gas, and how the different grades effect performance. I've heard certain chemicals they put in gas can eat these old engines up, is using lead substitute enough to combat this problem?

 

I've been running 87 RON unleaded for years without any detonation problems. I expect you are spending more than you need to. Try running it without the additives and give a lower octane rating a shot. If you (or it as the case may be) don't like it, switch back.

 

It's not really necessary to add a lead substitute.

The XJ will run fine on unleaded; you simply have to be sure not to neglect valve adjustment intervals.

Premium probably isn't even necessary, but I run it too.

 

My driveway is almost a mile long, ascends 300', with switchbacks and it's some really bad road. I really can't get out of 1st gear going up it and the motor gets quite warm by the time I get to the top due to the low air flow across the fins and the load. Since the octane formula is about compression and heat, I fill with premium to stay safe with the heat situation. Also, it idles better and runs smoother (can't feel the motor running through the handle grip). However, there is an Exxon station near my home that seems to have the worst fuel. Everything I ride or drive runs rough with it, premium or not. I know all stations usually get their fuel from one truck. They must be getting water into the underground tank or something...Anyone else know of a station like this?

 

What they said - lead substitute is not needed in XJ motors - they're designed for unleaded.

I usually run the 89 octane mid-grade stuff as a compromise between cost and trying to get as little ethanol in my fuel as possible.
(here in Ontario, ALL fuel contains some ethanol unless otherwise specified. "Regular" 87 octane is the worst with up to 15%. Mid-grade is mixed regular & premium. "Premium" can have 5% or even 0% ethanol depending on the station.)

 

I always burn premium or the highest octane fuel regularly available which is usually either 91 or 93 octane. When my bike was running before the oil leak it would run flawlessly with the premium. I also found that the engine wasnt as peppy with midgrade and regular and i also noticed that it would start easier with premium.

 

Actually, there are some things about gas stations that can make a difference.

I used to work at one, long ago...

Ideally, you want a gas station that has the covers for the underground tanks and sub pumps (you know, the metal ones that make that alarming sound when you run over them) raised slightly, and on a slight slope...flat lots or depressions are problematic. Rainwater pools around the tank lids, overflows the well around them and submerges them. The caps are supposed to be waterproof but aren't always.

One of our competitors down the street had a lot that ponded real bad over their underground fuel storage access when it rained hard, sometimes we'd tow in people who had filled there and didn't make it 2 miles before their car quit, the fuel was so loaded with water.

Also, when I was driving big trucks, we were always told not to fuel when a tanker was sitting there putting a fuel load in the ground. It stirs all the crap and water in the underground tanks, and if you're there pumping it out at the same time, you're buying some of that, despite the filters in the sub pumps and dispensers...probably more of an issue with diesel, but applies to gas as well.

We were always told to wait at least 15 mins after the tanker left...

And obviously, you like to buy from stations that do a lot of biz...their fuel is fresher and cleaner.

 

unleaded gasoline started production in 1975 i beleive. THUS, the introduction of the catalytic converter. or maybe it was 1976. somewhere around there.

anything built AFTER 1975 was built to use unleaded gasoline. so that leaded gasonline could eventually be phased out. if i remember right that happened sometime around 1995.

unleaded gasoline was formulated however so that any old cars still on the road that required leaded gasoline. would be able to use the unleaded formula without valve burn up.

leaded gasoline in them days acted as a lubricant for the valves. lead also caused carbon buildup.

my first maxim i bought brand new always used leaded gas. about 25k miles it ran like crap. CARBON BUILDUP. dealer said to use unleaded gas and the problem went away after about 1k miles.

if i remember right. the owners manual said to run leaded 87 octane.

i use the premium stuff in my suzuki. i seem to get a little better performance and better gas mileage. she has compression release valves in her though so i'm guessing it's a high compression motor.

 

I run the cheap stuff all winter and switch to mid-grade june-september. Needed premium when I went to california in august.

wiki "octane" some time. It's worth the read.

 

Pump premium, usually Mobil. We seem to have fewer fuel related problems running premium. Over in the aviation world, they're trying to do away with 100LL (low lead). Now these engines were made for leaded fuel, and they have quite an audience. They pulled it off with Nascar, and that's just 43 cars driving on Sunday.

 

I started running 93 octane in my bikes and i can tell it makes a difference more so on the 1100 and 650 no not so much on the 700 but the 700 runs great anyway.

 

I run premium in my '82 XJ1100 simply because the owners manual advises running premium....

 

Excellent points Snoww.

I've got a different perspective on unleaded fuel. I was raised in a 66 GTO and we had to add lead additives to the fuel when the change over occured (shortly after 75 where I lived). I subsequently had to have hardened valve seats installed in my heads to allow the use of unleaded fuels. Unleaded fuels lack the lubricative properties you mention for exactly the reasons you said. There was a great deal of effort on the oil companies to provide for the older cars but it proved that there was no reasonable means to provide the lubrication needed while still meeting emissions standards (you ought to read the white paper on this stuff, long and boring). Some cars could use the newer fuel if they backed off the timing and ran cooler but that dirtied (is that a word?) up the emissions. I could run my 68 GTO on unleaded but not my 66 Mustang or GTO so I'm guessing that the engineers saw the writing on the wall and made engineering changes to anticipate the future around 67.
Anyone here got an inside line on the happenings at the big three back then?

 

well, guess it won't matter what fuel we run anymore. EPA is close to upping the amount of ethanol to 15 percent. saying that cars built after 2001 can handle the extra amount.

i guess motorcycles can live with 30 mpg also.

good thing i bought an aux tank. might have to need it permanently just to maintain my original traveling distance BEFORE ethanol.

http://www.cnbc.com/id/39646175

 

I use Non Oxygenated Premium from the local gas station. It is kind of hard to find but. It lasts longer (Shelf Life) in my tanks. Also If you notice that the regular gas is only good for so long and starts to go bad in about 4-6 months. My lawn mower has had a problem over one winter. The tank was rusting and the gas turned brown. I was talking to the station attendant and he told me that the more ethanol in the fuel the more moisture it will attract. He also said that water and ethanol mix very well. So if the storeage tank at the station gets water in it you are getting water and ethanol mix in your tank and if it not a very high amount you may not notice a difference but bad gas mileage.
On another note: has anyone noticed that most newer cars have plastic gas tanks? I wonder if the car makers thought that water in the fuel could be a problem.

MN

 

i think plastic is cheaper then steel these days.

not having a rusty tank though would be a defenite bonus.

 

does running a higher octane cause timing problems with the pistons. Just wondering if higher octane can lead to late compression which will mess up the rythm of your pistons firing and ruin your engine?... i always use regular 87 fuel in my bike..it's cheapest and ignites with less compression usually making the bike run smooth (until i need to switch to reserve. vroom putt putt vrooom stutter putt). i have noticed the differences in the types from one gas station to another though like you guys mentioned.. maybe water in the fuel... it seems i can get more Km in one tank from SHELL or ESSO but less from stations like Mohawk etc. how many km/miles are you guys getting with regular gas? i can get around 200km before i have to switch to res. with 250km almost dry...

 

The resistance to spontaneous detonation and flame front travel speed are 2 different things. A higher octane fuel could have the same flame speed.

Due to gas tank size and engine size, you would only have a meaningful comparison to other 400's.
Seca 900's have 350km + range.

 

^ all very true points...

 

Non-corroding, lighter, and resists rupture/puncture better than steel tanks...