Transmission fluid change theories - Land Rovers Only

Disco Truck · 03-08-2007, 07:38 PM

I have heard that it is not good to change your transmission fluid on a high mileage vehicle if it has not been done in some time. My 98 has almost 125,000 on it. Since I bought it in 2000 never have I changed the transmission fluid. Bought it with almost 80,000 and no mx history. A bit brave, I know. SO, to change it or not to change it?

Muddy Oval · 03-08-2007, 08:00 PM

If it is burnt, maybe just leave it and let it die a slow death. If the fluid isn't burnt and it was done before you owned it like it was supposed to be- then it's due and should be done.

p76rangie · 03-09-2007, 12:51 AM

I can't see how changing the oil will do any harm. You should change the filter as well, which means dropping the pan, so you can give it a good clean.

Oil is cheaper than a rebuild.

Elemental · 03-09-2007, 05:11 AM

New ATF contains a fresh supply of detergents and
dispersants which can loosen the varnish and deposits
accumulated inside high-mileage, low-maintenance automatic
transmissions. On one hand, key components with tight
tolerances (such as solenoids and spool valves) may then be
exposed to the released debris. On the other hand, the
varnish and deposits may have been in a sort of
"equilibrium" in the automatic transmission. For example,
with the debris now removed from the frictional surface of
a clutch or band, the frictional properties have been
changed. Similarly, aged seals which may have had small
cracks once sealed by varnish and deposits may now be clean
and allowing internal hydraulic leaks.

Consider also that the seal swell additive in new ATF will
attempt to revive aged seals. And the friction modifiers in
the new ATF will try to provide the original level of
"slipperiness".

Again, the new ATF will simply be doing its designed job
which ends up revealing pre-existing problems in a
high-mileage, low-maintenance automatic transmission.

03-08-2007, 07:38 PM	#1 (permalink)
Disco Truck Member Join Date: Feb 2007 Location: Jupiter, FL. Posts: 18 Gallery: 0	Transmission fluid change theories I have heard that it is not good to change your transmission fluid on a high mileage vehicle if it has not been done in some time. My 98 has almost 125,000 on it. Since I bought it in 2000 never have I changed the transmission fluid. Bought it with almost 80,000 and no mx history. A bit brave, I know. SO, to change it or not to change it?

03-08-2007, 08:00 PM	#2 (permalink)
Muddy Oval Otherwise known as STEVE Join Date: Oct 2005 Location: Vermont Posts: 1,968 Gallery: 0	If it is burnt, maybe just leave it and let it die a slow death. If the fluid isn't burnt and it was done before you owned it like it was supposed to be- then it's due and should be done. __________________ 2002 Freelander 2000 DII w/CDL 1967 SIIA 109SW Former Rovers 2004 Modded "S" Disco, R.I.P. 2004 G4 Disco 2002 Modded Freelander 1995 Modded Disco 1994 D-90 #8 1993 NAS D110 1990 Range Rover County 1973 SIII 88 1972 Range Rover 2 door

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03-09-2007, 12:51 AM	#3 (permalink)
p76rangie Ian Matthews Join Date: Jan 2006 Location: Melbourne Australia Posts: 2,071 Gallery: 0	I can't see how changing the oil will do any harm. You should change the filter as well, which means dropping the pan, so you can give it a good clean. Oil is cheaper than a rebuild.

03-09-2007, 05:11 AM	#4 (permalink)
Elemental Senior Member Join Date: Feb 2007 Posts: 3,076 Gallery: 0	New ATF contains a fresh supply of detergents and dispersants which can loosen the varnish and deposits accumulated inside high-mileage, low-maintenance automatic transmissions. On one hand, key components with tight tolerances (such as solenoids and spool valves) may then be exposed to the released debris. On the other hand, the varnish and deposits may have been in a sort of "equilibrium" in the automatic transmission. For example, with the debris now removed from the frictional surface of a clutch or band, the frictional properties have been changed. Similarly, aged seals which may have had small cracks once sealed by varnish and deposits may now be clean and allowing internal hydraulic leaks. Consider also that the seal swell additive in new ATF will attempt to revive aged seals. And the friction modifiers in the new ATF will try to provide the original level of "slipperiness". Again, the new ATF will simply be doing its designed job which ends up revealing pre-existing problems in a high-mileage, low-maintenance automatic transmission.

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