: 1969 deville rear differential fluid

04-16-07, 04:36 PM
Hey guys,

does this fluid need to be changed? and if so with what? in the manual it just says "the special stuff" not the universal fluid. what should i use?

04-18-07, 01:18 AM
My manual says to check it and it should be within 1/2" of the lower edge of the filler hole. But that it only should be checked if you've got leakage. It says for the standard differential, to use either SAE 90 multi-purpose type gear lubricant conforming to MIL-L-2105-B or the special stuff . But if you have the Controlled Differential, you _have_ to use the special stuff. Are we looking at the same manual?

04-18-07, 10:06 AM
i am looking at the service manual from 69. basically whats the controled differential and where can i get the "special" fluid? i called 4 dealerships and they just told me to use regular 90w gear lube. they didnt have any idea what the controlled one was.

its not a positrack, so i shouldnt need the additive for it right?

04-18-07, 12:26 PM
If you dont have a limited slip then you do not need any additives. What I do suggest you do is drill and tap a hole at the bottom of the housing, there is no drain plug for these rear ends. After tapping it you can just stick a bolt with a rubber washer on it and you will be fine.

04-18-07, 02:36 PM
why cant i just do it the normal way and just losen the bolts?

sorry side question, when im changing the transmission fluid, i take the pan all the way off right? and then do i need another gasket or seal? or just bolt it back on?

04-19-07, 03:13 PM
theres a local transmission place in KC here thats got a special on flushing the transmission for $50. i think that im going to take them up on that, and they can flush the differential for 20.

04-19-07, 04:02 PM
Flushing the trans without changing the filter is like kissing your sister. You don't get anything out of it.

You don't flush the rear, you remove the rear diff cover and drain it. Unless you have a leak or hear a growling noise or it breaks, there really is no reason to do this.

04-19-07, 04:18 PM
changing the filter is an extra 25. lol i dont want to kiss my sister lol so ill just make sure they do that.

04-22-07, 12:13 AM
I'm not sure of 69s but my 168 doesn't have a drain plug and it doesn't have a rear cover that you can take off either It has just a fill plug that you would suck the old oil out with a pump and could then refill.

Cadillac limited slip and chevrolet "posi-traction" were two different differentials. I'd have to check my manuals to see if the Cadillac differential needed and special additive, but I don't remember it needing any.

06-01-07, 11:09 AM
hey guys, sorry for the thread jack.

Raider1v1, I just joined and can't send pm's, I live in the KC area and wouldn't mind finding some other owners to meet up with occasionally. Do you know any local groups? I've got a '69 Sedan DeVille.

moderators, I did try to search within the forum but wasn't successful