39 MPG. A fluke?
 

Hi all,

So I bought my first ever MB about 3 weeks ago, a 1983 240d. I changed the oil, fuel and air filters and got 24 MPG on the first tank. I filled up again and took the car for a road trip to the WA coast. After 273 miles the fuel gage showed just under 1/2 a tank. Naturally I thought the gauge just being wonky but no, I filled up again - topped all the way off - and put in just over 7 gallons = 39 MPG on the trip! That's insane, yes? Is that just a fluke? I'm using ATF as an additive, by the way. And I google mapped the trip - the odometer is accurate.

Good for you! By the way, how does the car run when ATF is added? I was considering it in my 300D but wasn't sure if it would destroy the motor or not.

Unless those 273 miles were all downhill, I'm going to say no way.

Agree.
 

I drive like I don't really want to get to my destination and the best I ever got out of a 240 D was ~33-34. These were highway miles within the speed limit.

Yeah it is possible, but driving conditions are a big factor and driving habits.

I was getting 28 - 28.8mpg in the 80 240D. before we went on our last trip to Portland, Or. last summer, I checked the tire pressure and it was where ever the tire shop put it when I had the new tires installed.

Side wall said Max pressure, 44#, so I upped it to 42#`s.
first tank from Lathrop, Ca. to Cottage Grove, Or. was 32.73mpg.
Then a week of driving around Portland, we drive 125 miles back to Cottage Grove and fuel up., 32.01mpg.

Finally back to Lathrop. 36.88mpg. this leg is after driving over the Siskyews which is a good climb from Ashland, Or to the Ca. border then it flattens out.

Last week we went to carson City, Nv. over the Sierra on hwy 50 which gets up to 7400ft. then the valley floor is 4500- 4600ft. a week of running around town, we fill up for the trip back. 32.74mpg.

The trip back, we used Hwy 88, and it climbs to over 9000ft. then the west side is mostly down hill to sea level. fueled in Santa Cruz a couple days after we got home, and then some in town driving. this tank showed, 38.78mpg.

We cruise along at around 65 on the Hwy, but climbing the steeper hills, then it is some 3rd gear.

we have Diesel #2 out here, not cold enough for #1, and with the cool weather helps on the milage some.

Charlie

That is some pretty excellent mileage and would only be possible with very slow driving like 45 to 50 IMHO. A short fill like that is not very accurate either and did you count the quart of atf in your fuel calculation? It's fuel too.

all in all it is possible but only on the far end of believable with some fuzzy factors such as inconsistant fills, etc.

Now duplicate it four times in row and check your odometer against the mile markers and get back with us.;)

Thirdrem in your neck of the woods, kerosene would be much much better and MB recommends it. Check your owners manual.

I've only had the car a few weeks but so far it's running well - I'm cautiously optimistic. Two different MB mechanics have told me that they use ATF if their disels so I doubt that it will do damage to your motor. I'm using a quart per tank.

We averaged 61 MPH on the trip (58 there, 64 back (not including small trips when we were on the coast)).

You're right, I forgot the aft, that brings it up to 7.25 gallons, which = 37.65 - a little less remarkable.

The google maps comparison was within 3 miles, the difference being small trips we made while actually on the coast, so I'm confident that the miles are accurate. I'm taking the car to San Francisco at the end of March - we'll see how it does then.

Not commenting on the mileage, but the quart of ATF shouldn't hurt the Mercedes injector pump, and the minor amount of coking shouldn't be significant.
The mechanics who deal with the Cummins engines with the infamously touchy Bosch VP44 injector pumps have been recommending ATF as an additive since the low sulpher diesel fuel currently available doesn't have enough lubricity for fuel-lubed pumps.
(Coking is not a factor in the Cummins because AFAIK it is direct injection, no precombustion chamber.)

I've been told kerosene will destroy the motor, and it is so flipping expensive up here, it is not ideal. We get #1 diesel year 'round and it works fine for the other MB diesel owners up here. I don't know. But I want to try the ATF not for MPG but to kind of clean the engine up. Hmm, well take care and God Bless!

Just a thought, but the tank in my 240D gurgles and burps a bit after a fill up. If I fill up, go away, and check it again later I might have to add another gallon. Rinse and repeat a few times.

So although you might have only added 7 gallons to fill it up, if you gave it a few minutes you could find it still needs more topping off.

The ONLY thing MB recommends kerosene for is EXTREME cold weather thinning of D2 to prevent gelling.

the ATF in the fuel is for lubrication or cleaning (although, it's cleaning properties are overrated...)
Kero would provide ZERO lubrication, and in warm areas, it'll be bad for the car.
best is biodiesel, 2cycle oil, or non detergent motor oil, as ATF may work, but the red coloring could get you fined from the highway patrol, or some such, and it's friction additives, are not good for the IP.

straight kero can damage the IP, and cause wear on the cylinders/rings, but mixed up to 60/40 I believe is what is recommended in the owners manual, for mixing with #2 Diesel to prevent gelling... and I am pretty sure, #1 is just a certain mix of #2 and kero...

Yeah, I'm gonna put some 2cycle in it. I don't think I'll do the ATF, I've seen some info that said it would damage the motor. That would be nice to get 35 MPG though, but I wont risk the motor for some better fuel economy.