Greetings. I am long overdue to change the trans fluid on my '85 300TD. (I guess i didn't want to wake a sleeping dog). Would it be advisable to use synthetic oil on the refill? or best to stay with factory spec (what type is that btw?)

Also I have read some posts that suggest draining the converter and some that say not to. Any input there?

Thanks!

My signature car has been using Amsoil universal ATF for eight years with no issues at all.

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'83 300D, 126K miles.

I'd try and drain the converter. It didnt line up for me after numerous tries, so I didnt. After all, I overfilled the trans and had to drain alot back out.

As to fluid, if it hasnt had synth, you said it " let sleeping dogs lie." I used regular Vavoline high milage ( forget the spec, but likely Ford) which was stock spec'd in my 95 AND 96, and all is well. My later year 96 i believe had synth in the diff, and now it has fresh G4. But if I keep the ride, it'll be swapped with Red Line synth, type as spec'd from the factory. imho, keep it the same.

The original spec for an '85 TD was probably Dexron II or one of the variants (IID, IIE). Dexron III which is what's still available today but sometimes not labeled as such wasn't offered until the '90s, IIRC. The only fluid I see still labeled as Dex II compatible is Redline D4 ATF. Dex III is backward compatible with Dex II so maybe other ATF manufacturers don't bother mentioning it.

Definitely drain the converter. What post says to not drain the converter? Why change only 1/3 of the fluid?

Sixto
87 300D

The easiest way for a correct refill is to measure what you drained and replace it with the same amount.

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'83 300D, 126K miles.

If you confirm that it's at the correct level before you drain

Sixto
87 300D

If you have any leaks they will probably be worse with synthetic oil. Otherwise there should be no risk. Draining the torque converter is not difficult although it's hard to turn the engine by hand and watch for the drain plug to come around at the same time. I use a mirror under the torque converter while turning the engine with a socket wrench.

See post #9 in this link for a picture of that process.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
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Don't forget to index the crank pulley with the TC drain for next time.

Sixto
87 300D

You can use a large screw driver to lever around the torque converter while watching for the drain plug. It turns relatively easily. That way you don't have to crawl out and back under the car fifty times.

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Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
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