I just got my 55 Super 88 off the shipping trailer and drove it into the garage. There is a significant red puddle under the transmission where the driveshaft enters it. Here are some pics. The dipstick is dry when it is idling.

Any idea how to fix and what ATF fluid I should use? I hear Dexron III is the best. Any advice is appreciative...dont want to wreck the car 20 minutes into owning it.

Thanks,
TOM

 

Tom, any Dexron / Mercon fluid will do. If you find one that is IV, V or VI that will work too.

Here's an option:

 

X2 what Olds64 said. All the numbered Dexron can be intermixed and are compatible with each other.

It looks like you leak is the rear transmission seal, one of the easier one to get to and fix.... Tedd

 

You've got some good advice so far. Here's another thing you might want to consider. That slip yoke calls for lube every 5,000 miles. Instead of changing out that plug for a fitting every 5,000 some owners just install the fitting and leave it, making the job a bit easier. It's best not to use a pneumatic tool to do the lubing. Just give it a "hand job" lubricator.

 

You may want to check the slip yoke for leaking out the yoke itself. Some of the yokes use a expansion plug to keep the oil from leaking out. If the leak is at the back of the extension housing, then the oil seal is the culprit.

 

The gasket part number is 8611998
The seal part number is 8617123
The "O" ring part number is 8617119

 

Is that fitting you need to install just a zerk fitting/grease fitting? I'm not sure that lube was ever done, just judging how dry every grease fitting looks....if I put the fitting in and lube it, could that stop the leak?

 

I just had mine rebuilt a few months ago and with the exception of the tail shaft seal leaking it was a great job. I imagine it was just a bad seal. I will just get a new one and replace it myself. I use the high mileage Dexron that is O'Reilys brand. I don't know that it is any different.

 

Yes it is a conventional zerk. They come in different thread sizes and different angles, so choose what is appropriate for your likes. Be sure that the zerk you use is clean inside and out. The 1955 Olds Shop Manual calls for GM special lubricant 563598 or 567196 every 5,000 miles, until lubricant appears at breather groove at end of rear bearing retainer. I don't know if that lubricant is still available, nor do I know its formula. (The two numbers are due to two different size containers; it's the same grease.) It is intended for use with synthetic seals (so the seals will not be damaged). I have always used the same grease that I use on the rest of the chassis. The Hydramatic still has the same seal it came with and it never has leaked, hence I assume that my approach is acceptable. It's best done with a hand operated grease gun. If it's been a while since it's been greased, it will take a lot of pumps to fill the reservoir. I don't know if greasing it will stop the leak, but I suppose that you could try it. If it does, it will save you changing the seal.