A couple weeks ago I changed the fluid and filter in my 722.435 transmission. When I filled up the tank yesterday I noticed that my MPG dropped to about 25, when in the city I seem to get 28 without much variation. It's not very accurate experiment, since half of the tank was burnt before the change, and it got warm so I've been using the AC.

Is there way way that I could have done something to the transmission/torque converter to cause the change, or is it just a coincidence? Also, since the fluid change I've been idling significantly higher, about 800-900 RPM sometimes instead of 600.

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Jay Kickliter
Chasing 'trons (my thoughts and tutorials on electronics and stuff)


1995 E300D-Black on Black

The idle speed is a weird thing.

ATF has been known to shear significantly as it is used, so fresh fluid could have some effect, but I wouldnt see it as higher than 0.5% or so.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Run a whole tank on the new stuff then check again. I don't see how it could possibly affect your mpg. If anything it should improve.

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