i drove the car about 1 quart low on tranny fluid for 2-3 weeks. during that time, it flared a little maybe once in the course of driving 50 miles. i filled it up the rest of the way, and now it flares really big (the flare is more intense than before) once in the course of driving 30-50 miles. have a done irrepairable damage?

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1985 300D Turbo "Eunis"

I drove mine about half a quart below the "min" mark on the dipstick for probably 1.5-2 months, added a quart to bring it right up to "full" and shifts were smoother, otherwise no difference.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

My 82 300D leaks ATF slowly from the front seal and gets low sometimes. I'm not really sure that 1 qt low would induce flairing.

But, next time you change ATF consider switching to synthetic. That stuff really cleans out the gum in the valve body and has helped my transmission shift much better. I had a flair issue when (very) cold and synthetic ATF stopped it quickly.

I also felt a few flairs in my 1987 300D and switched to ATF - no more at all.

Synthetic AFT is pretty expensive (Mobile 1 ATF) but compare that cost to a transmission rebuild.........

Ken300D

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

I may switch my car to synthetic, as its had all its internal seals replaced about 1.5 years ago, so I should have to worry about leaks.....

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

oddly enough, i used Mobile 1 ATF. In fact...well, here's the whole story.
bought the car a few months back. per advice from a relative, i decided to change the transmission fluid/filter, as i had no idea when the last change took place. so i drained the old fluid (yes, i emptied the torque converter too) installed a new gasket, and (here's where i messed up) tightened the 6 pan bolts as hard as i could with a ratchet. a few weeks later, i noticed it was leaking fluid. unfortunately, i was about to go on vacation for a week, so i put a drain pan under the car and left for florida. upon returning home, i noticed that it wasn't leaking anymore, and when i checked the level, it was low, but there was still fluid in there. so i drove it, and it flared a little once in a blue moon. two weeks or so later, it started leaking again, so i figured, "maybe i didn't tighten those bolts enough" and i go under there and crank down even harder on those things. while explaining why i needed a certain part to an employee at auto zone, my transmission leak came up in conversation. she said that if i over tightened the pan bolts, i had probably split the seal. so i took the pan off. and WOW...that was one mangled gasket. it's a wonder all my fluid didn't leak out overnight. not only that, but the pan was badly bent where the bolts met the bottom of the pan...that area was pushed up even with the top of the lip (i took pictures...it's hard to tell but it is badly bent) so my dad goes to the junkyard, and (just my luck) the one 123 they had there had just been removed a few hours prior to his arrival. so i, being the impatient kid that i am, go and buy a brand new pan for $83 (ouch!), and a new gasket. the guy at the junkyard told my dad that the best way to tighten the pan bolts the right amount (without a torque wrench) was to use a bolt driver instead of a ratchet, and tighten as hard as you can with that. less leverage=less torque i suppose. so, i figure better safe than sorry, and spend an entire day with my dad driving all over virginia beach, norfolk, and chesapeake, trying to track down a torque wrench. we never found one that had the right scale on it. so my dad decides to go with the bolt driver idea, and we spend a long time wading through the junk in our garage, trying to find the right size bolt driver. we never did. we found the size right below, and the size right above, but not the correct size. my dad went the creative/cheap route and wrapped some rubber tape around an 8-inch extension to form a makeshift handle. attatched the correct size socket and tightened away. just to be safe, he didn't tighten them as hard as he could. it's been 3 weeks now, and no sign of a leak. i used mobile 1 ATF both times when i filled the tranny (my wallet is still sore), although i didn't see any sense in emptying the torque converter the second time. i drove around about 2 (3?) quarts low for a few weeks, during which period my transmission flared once in a blue moon, but shifted real smooth otherwise. added a few quarts until i was at the top notch on the dipstick (i checked the level immediately after driving the car around for about 5 minutes). now my trans. flares really big once in a while. hopefully an adjustment of some sort will remedy that, though. i'll have to do some reading. learned a huge lesson through all of that mess, of course.

__________________
1985 300D Turbo "Eunis"

here is a pic of my poor transmission pan:

__________________
1985 300D Turbo "Eunis"

Did you notice any improvement in using Mobil 1 synthetic ATF over the DexronIII? I have been thinking about making the switch, but Mobil 1 is so much more expen$ive than Dexron....like 4x more

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)