This is a 1985 300SD, new $3000 automatic, ok Michelins, o degree sea level to about 500 feet and doing 70 mph.
Before the trans, at the same speed, was 23 mpg.
After the trans doing 75-80 was 22. (driving like a mad man)


I'm happy with the 26.3 but i wonder what 65 mph will do.(can i go that slow?)
Don't know the rear axle ratio and this is a CA/Emissions car with a need for a new air filter.

Any comments..... additives to use, trans oil to use....

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Rick & Michele in California
1985 300SD Turbo Deisel
300,000+ miles

1963 Mercury Meteor Stationwagon
1959 Montgomery Ward Silver Pigeon Scooter & matching bicycle
1974 IH Scout 4x4

You would get a few more MPG simply by getting rid of the Kalifornia emissions cr@p.

I simply can't get above 22.5 on my wagon.
And I can't get below 27 in China....{got over 30mpg 2 tanks ago} Have to fill up tomorrow....

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

My 85 SD does about 29ish MPG GPS verified. I drive mostly 65-70mph open road.
Valve timing is important on cars with taller rear axle ratios for max mpg. Engine efficiency needs to be at the proper rpm.
Check your chain stretch with a dial indicator. Offset keys are available to advance it where it needs to be.

Lately 27.5, on cheap fuel, have resorted to decent stuff, all dino. We'll see.

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83 SD

84 CD

The best I have done on the 300SD is 29 mpg at 65-70, mostly flat Interstate highway with no traffic obstructions, over a 250 mile trip.

Valve adjustment is very important to engine efficiency.

Slowing down a bit will bring a noticeable improvement. It seems these cars are very heavily into the turbo at 80 mph.

You don't still have the big trap oxidizer do you? The football under the hood?

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Ken,
I still have all of the emission crap, with the trap being replaced in 95' by the dealer. How much of a gain of milage can i get, if i'm doing 26, if i change it back to non-emissions? I mean as what cost.
OK so i will do the work to go non-emissions, change the rear axle ratio, etc....
How much wear does it take on the trans if i'm shifting down to third up a hill and i'm going up and over 4000 rpm for a few minutes?

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Rick & Michele in California
1985 300SD Turbo Deisel
300,000+ miles

1963 Mercury Meteor Stationwagon
1959 Montgomery Ward Silver Pigeon Scooter & matching bicycle
1974 IH Scout 4x4

My 82 300SD with 101,398 just got 30.42 MPG. A near 25% gain from when I purchased old "Bobalina Fitzgerald" last year (24-25 MPG).

4 new Michelins
New Air Filter
EGR Modification
ALDA adjust - 2 turns CW (PO had set to rich)

I made it to Columbus, GA and back on half a tank last Saturday, its a 280 mile round trip, averaged about 85-90 mph, but got quite a bit over 100 on some down hills. That seems pretty good to me, but I've never done an actual mpg calculation, since I fill up from my garage with biodiesel and have no measurement of how many gallons I put in...

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Ich liebe meine Autos!

1991 Mercedes-Benz 560SEL | Megasquirt MS3-Pro | 722.6 transmission w/ AMG paddles | Feind Motorsports Sway Bar | Stinger VIP Radar | AntiLaser Priority | PLX Wideband O2 | 150A Alternator | Cat Delete
1981 Mercedes-Benz 300SD | Blown engine, rebuilding someday...
1981 Mercedes-Benz 300SD | Rear ended, retired in garage.
2009 Yamaha AR230HO | Das Boot

Excessive speeding? It ain't excessive till I redline!

You will not see that much of a jump in mileage if you get rid of the trap.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

28.8 mpg is my record so far, maintaining 65 mph....

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
-
Do I miss being a service advisor ???

Diesel Kleen is supposed to boost your fuel performance, up to 5% I think. It does make my car a bit quieter.

jeff 1991 300d

Nothing significant. Transmission couldn't care less. Engine won't really mind but I think anything over 4700 or 5000 or something is supposed to be hard on them for long periods.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

My record is about 28 mpg in my 85 Kalifornistani 300SD. I have made some modifications though (a cherry bomb, franken turbo, and somebody plugged the ARV) . I also run Power Service (white bottle) in the summer.

To get better mileage the first thing you want to do is make sure you had the trap ox recall work done. If your getting 26 mpg it sounds like you have. Even with the recall work you need to log some highway miles to keep it clean. To really clean it out, find a steep long hill and floor the pedal up it. When you get to the top let off the pedal and down shift. Driving up the hill heats up the trap cat, letting off the pedal and down shifting gives the hot trap cat a burst of oxygen to burn and blow the crud out of it.

Some other things that can improve mileage :
1 properly adjusted valves
2 proper valve and injection pump timing
3 Clean air filter
4 If some how your ARV ceases to function.
5 If some how your EGR ceases to function
6 Fresh transmission fluid in your transmission (provides better coupling)
7 improved exhaust flow
8 better turbo

I have found that my 85 SD gets its best mileage between 70 and 75 mph (but then again I have modified my turbo to work better at this speed ). The 85 model has a different rear end in it so its cruising speed is a little different than the previous years.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

Isn't the rear ratio 2.47 for CA compared to 2.88 for all others?

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R