I have an '84 DL automatic. I drive about 80% highway and struggle to get 22mpg. I don't drive particularly fast. I just got a tune-up, put in a new thermostat so the temp gage reads about half, and put in a new Bosch O2 sensor. What else could I check? Any ideas? The transmission does have some problems. On cold mornings it sometimes takes a minute to warm up enough to produce vehicle motion.
Thanks
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Ben

Just for reference, you might be able to get a couple more mpgs, but I can't suggest how. I have an 84DL 244 auto with 320K- an early 84 with the unheated sensor, running Avid T4s at 32lbs 90% highway 100 miles a day, no load heavier than a full size spare, occasionally wound out in first gear. Been using synth oil before beginning accurate mpg spreadsheet a couple years ago. The mileage runs 24.5 in the summer even with A/C but drops to 23+ in RFG time.

The 89 auto tops 25 as a grocery getter. The 79 kjet auto barely crests 21 and its odo runs about 5% to its benefit.
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Art Benstein near Baltimore

I don't know if your model has an in-tank fuel pump. I just fixed mine on my 1990 240. I went from 18 to 21 mpg.

I agree. My '85 gets about an average of 25mpg. Thats not a bad thing though... maybe gas prices are so high, that it seems like your using more fuel??? Like I think (it's at least $2 a gallon for the cheap grade). :-) Michael

I averaged around 26MPG in my '83 B23F before I started messing with it, but I have the M46 tranny. 22MPG is not bad - it's at the low end of normal. By tune-up I assume you mean new plugs, cap & rotor? That's a good start. Now how are your spark plug wires? Older wires that are stiff & brittle can leak voltage and arc, especially in damp weather (major cause of no-starts), and can cause subtle misfires and hence lost MPG. Check the base ignition timing at idle - should be 12* +/- 2*, unless you have a problem with pinging, in which case you can go a bit lower (like 10*). Check your vacuum hoses for leaks/splits. Those little hoses are cheap and easy to replace, but can cause you big headaches if not looked after.

That takes care of the common engine areas - now it sounds to me like your tranny might be the main problem. Check the fluid level, and do a flush if the fluid is dark. You can find instructions on performing this procedure in the 700/900 FAQ. You'd be amazed how sometimes a tranny that feels like it's on it's last legs can be cured with a fluid flush (remember, I said SOMETIMES.) You could have slipping at speed, or even excessive slip during shifts that is causing lost mileage.

HTH...
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Speed Racer, '83 240 R, '74 164 E, '93 940 OL1 (Manchester, CT)

Ben,

My '91 240 gets 22-24 mpg around town. Bricks are not aerodynamic.

Mak

I don't know if it will help the mileage but the tranny sounds like it is either low on oil or, more likely, in need of flushing and new oil. My daighter's '84 240 was reluctant to shift or even move when you first started it. (sort of like me) I didn't do a full flush but I did drain the tranny and replace with fresh oil. After a few runs, the tranny is much better starts moving right away and shifts smoother. I plan to get some tubing and do a real complete flush this spring.

We do about 50-50 street and freeway drives, mostly short distances of 20 miles per trip. We get about 22 mpg. The last long trip we took, we got 29-30 mpg on the freeway with some city traffic mixed in. I don't think your car is too far off the mark. Of course our 240's with standard trannys do better. About 26 in town and 30 on the road.