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My best fuel mileage ever!!

RichP said:
A 1 mile commute and you DRIVE, man thats the severest duty that you can put an engine thru. That engine NEVER warms up, never comes out of cold loop or has the opportunity to burn off moisture from condensation in the oil.
Click to expand...

Amen. Internal rust from this kind of use kills more cars than body rust, I read many years ago. It's a pain for someone w/a 1 mile commute, isn't it? What about some kind of engine heater in such cases? It would certainly be cheaper than having to add a 4 mile detour to every commute trip.
 
Hey Rich..That is one of the reasons I run Synthetic motor oil. I live only 1 mile from my work and I only have to drive 1 mile on the days that I don't have to take my son to the babysitter. On the days that I do have to take the son to the babysitter I have about a 10 mile drive with about 6 miles of interstate. Only in the summer do I really only have a 1 mile drive, because my wife is a school teacher and keeps our son then. Anyway, my wife drives a 99 Corolla on her 45 mile commute to where she teaches. Maybe I need to ler her drive my XJ once a week to school, haha.....Rusty
 
How does running synthetic help this short-trip problem? If it does in any substantial way, that might be the best reason I've heard yet for using it.
 
Well beyond better lubrication and being better on startup I don't know that it would help that much. Performing on startup like a thinner oil I thought was supposed to be a good thing and getting lubricant to the cylinder walls, etc more quickly. I don't know for sure but I thought that synthetic was supposed to adhere to objects like cylinder walls, valvetrain, etc better than conventional, even though it is thinner at cooler temps because of it's molecular composition..Atleast that is what I have understood from prev posts about synthetic. These factors plus from what I have gathered on here about synthetics (Amsoil and Castrol atleast) having stronger additive packages. No matter what I am sure it is best to have longer trips if possible to burn off the carbon in all parts of the engine and the oil. Oh well, I don't think I am gonna alter my route too much just to burn off crud from my oil, since I have too many other places to go outside of work, haha. I might add that with my castol syntec, the purolator pure one oil filter, and the reusable Amsoil oil wetted air filter, my oil "appears" cleaner much longer than it did with the conventional oil, cheapo oil filter, and paper air filter. It's about all I know to do at this point to make any improvement in how long my engine will last. Only got 75,000 on it so far, in fact I just paid it off last month!!!!! Yipee..Maybe I can start doing some mods too it finally...Never can tell though with a wife and a 10 month old baby what costs can accumulate!!!!....Rusty
 
I hear ya, but I think I would get a decent mountain bike for a 1 miler, save on gas and good excersise. The condensation not burning off is not good but day after day of that engine essentialy being in perpetual cold loop, running very rich for one mile, has also got to be tough on the cat day after day because while it is in cold loop the emission/fuel control is not running yet. Swapping the cars once school opens is also a good idea and one I will have to remember come sept :doh: as my wifes commute to where she teachs is less than 3 miles, my daughter will also be driving her TJ to school, 4 miles for her this year now that she's a senior and can get a parking pass. I may end up driving mine only once or twice per week on service calls. Now that you brought it up I realize why my sons last two cars oil, caddy eldorado and 89YJ, got so dirty so fast, it was that 4mi into school and 4mi back home every day, that caddy eldo never even warmed up and the throttle body injectors got carboned up on a reguar basis as did the webber in the YJ, sheesh, talk about not seeing the forest for the trees....
 
so...three miles is a bad idea...well shoot. that how far my school is from me home. but the heep seems to warm up alright in the mornings. and the famous "white smoke" that comes out of a cold engine is gone by the time I reach my mailbox at the end of a long twisty driveway.

should i let my jeep warmup before I hurry to class?
 
I've never quite figured out whatever mojo or spell it is that makes some XJ's get better economy than others. My Ex's 88 5-speed, a box-stock base model 4.0, bought new, never broke 20 or so, no matter who drove it. My 87 slushbox delivered a pretty steady 23 over 100+ thousand miles even after the oxygen sensor literally fell off. On road trips pulling a trailer and carrying 3 bikes and a full load of stuff it would deliver a healthy 19. My stepson's 93 slusher was good for the low 20's most of the time despite his lead foot. My 95 5-speed has usually held around 20, and dropped to more like 17 in the same conditions that the 87 did at 19 or 20. I just took my new 99 5-speed on a day trip and hit 24.8.

I never put mouse milk in mine. Dino oil and good filters do it for me. I suppose that theoretically, a 4.0 might last for 500 thousand miles instead of 300 if I did something else, but by then theh roof rust and the floor rust will have met in the middle and I'll be braking with my feet.
 
1989 120k miles 4 door 4wd

got 21.5 on my last tank about a month ago...truck doesn't even run now, still haven't figured out why.......
 
I usually average 17-18mpg depending on how fast I go on my 45mile commute, but I've tried to keep my speed below 60mph as much as possible... my last tank got 19mpg :)

I recently drove from from Delaware to Alabama and back. coming back, I got one tank at 22.2mpg, the best it's ever seen. all highway except for 5 miles of the trip, average speed 67mph (cruise control). my trip down was around 18-19mpg, but I was going a bit faster... 72-75mph. slower speed definately made a difference. 4 door, A/C on.
 
My best milage was 390 miles on 19.0 gallons which is just over 20.5 mpg at 65 - 70 mph round trip to OCMD. I did manage to get 17 mpg on a 170 mile trip at 85 - 90 mph. These were both done in my 1991 2 door XJ. The engine had less than 10K miles on it. The only modifications are a Borla header & front pipe, flowmaster 40 series muffler, rubicon express 62mm throttle body,3"BDS lift, and 30x9.50x15 tires.The Gearing is stock 3.54. I will have a MSD coil & K&N FIPK installed soon. WIll update it then.
 
Good point and true DENLIP bout the formulas in different states, this is a fact being as I am from fla and lived in wis and now in NC and the formulas are all different. But aside from that the only thing I can think of is what time of year was this trip? I mean of course we will get better mpg in cooler temps than the heat of the south. I noticed a 2mpg bump when I moved here from fla. in the winter or if it is cold out like driving at night.
 
Adding to my post above about the mysterious variations, I mentioned to my son that I got almost 25 mpg on my new 99, and he said oh yeah, he regularly gets 24 or 25 even with a good deal of city driving from his 96 5-speed, and was wondering what's up when he recently measured 28+ on a trip. Now the kid drives a van for a living, and I know he's pretty smooth, but that's still pretty unusual. His previous car was Jetta eco-diesel that got something like 50 mpg, though, so he's had a hard time adjusting to having merely the best XJ mileage around.
 
I barely get 15 around town with 4.10's and 30 inchers. Usual engine mods including synthetics and in the diff.
 
best ever was Albuquerque to Dallas...downhill with a tailwind I got 27MPG. I had to stop at half tank 'cause my bladder was gonna burst. 3" lift on 31s and Im gettin 19. Which dropped by 1MPG after lift. I cruise 65.
 
wildman said:
1989 120k miles 4 door 4wd

got 21.5 on my last tank about a month ago...truck doesn't even run now, still haven't figured out why.......
Click to expand...

Mileage was too high. You outran your gas tank. It'll take a day or two to catch up.

(I can say this, because I read the post that says he got the Jeep fixed!) :)

Den
 
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