Our 1983 300D with about 165,000 miles has been slipping for a few years between the 3rd and 4th gear shifts. Last summer we had the tranny fluid changed and it seemed to work much better for a few months. It now seems to be slipping more and our mechanic says vacuum and other settings are OK. Would replacing AT fluid with synthetic help eliminate the slipping and if so, what brand/type should we use? We won't be keeping the car much longer but if a fluid change to synthetic could help, I would do it.

I wouldn't recommend switching to synthetic. It will probably cause some leaking, and if you're not going to have the car much longer, then just wait until you're ready to get rid of it then change the fluid and filter once again, and hope it helps. You're probably ready for a rebuilt tranny, but if the rest of the car is in good enough shape to justify one, then go ahead and do it. If not, just let it go and tell the prospective buyer about the slippage. My '80 300SD's tranny has been slipping for about four years now (3rd to 4th gear) but I'm not going to put another tranny in it, the body just has too much wear and tear, and I've decided that when that car is no longer serviceable, I'm probably going to pull the interior, which is in absolutely mint condition and the engine as well and junk the rest of it. And if I don't sell my 300E, I'll probably switch over to driving that every day, although I hate to accumulate the miles on it. Anyways, good luck!

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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'85 BMW 745i Turbo