A Couple Simple (Dumb) Questions on My '46 with 350/350

[Dan in Pasadena]

I should know the answers to these questions but I'm looking for some advice.

I want to change the rear end gear oil and don't know what to use for certain. My truck has a Jag rear end of unknown origin - there must be some kind of identification on it but I haven't found it yet - But I know Jag rear ends are essentially Dana 44's so can I just use any name brand 90 weight gear oil in it? What do you suppose the capacity is? If not, what would you recommend? If you recommend a synthetic, since I don't know the mileage or history on this rear end is there any concern (as I have heard on higher mileage engines) in switching from dino oil to synthetic...leaking? Any other bad outcomes to expect?

Engine oil: I plan on using Castrol GTX 10w30; or I suppose I could go to straight 30w, as I have no idea what's been used in it in the past. It isn't using oil, it isn't smoking and runs excellent as is. I don't want to go to synthetic on this engine.

Last: The tranny is a TH350 and I've never had an older auto before. WHat fluid do you recommend? Since I don't know its history should I pull the pan and ...do what?

Pardon my stupid questions but you guys that have started projects before on cars/trucks that have engines/trans/rear ends of unknown origins must have an opinion on these simple questions. Any advice appreciated.

[jjjmm56]

Is the motor and trans in the truck? Reason being I like to pull the pan and check out the lower end. I once got a motor that ran like a raped ape in the doner car and when I pulled the pan I found pistons skirts that were cracked. Also good to replace gaskets. On the trans I replace the seals filter and add a shift kit. Most people don't have problems I'm not that lucky.

[Dan in Pasadena]

Yeah, motor and trans are installed and running excellent. I think the Jag has 2.88 gears - which I suppose is why it doesn't exactly accelerate like a raped ape; though it ought to as the truck doesn't weigh much. I haven't put it on the freeway yet to see what it turns at 60 or 70 mph, but it can't be much.

NO immediate plans to pull the oil pan but I'm sure I will - assuming I can - haven't looked to see if a cross member is in the way.

[Dan in Pasadena]

Originally Posted by Dan in Pasadena

...I want to change the rear end gear oil...My truck has a Jag rear end...(which) are Dana 44's so can I just use any name brand 90 weight gear oil? What capacity?

What ATF do you recommend (for the TH350)? Since I don't know its history should I pull the pan and ...do what? ....Any advice appreciated.

Tried to edit my tome down to the main questions. A little help?

[solidaxel]

Originally Posted by Dan in Pasadena

Tried to edit my tome down to the main questions. A little help?

Here is my $.02

I don't think Jag is any different than a Ford center section does it have Posi, if so it will need some additive for the clutches (Ford posi additive).
As far as the TH 350 all I have ever used is Dextron unless it has some exotic clutches in it. The 350ci will run on just about anything except 5W!!

[Dan in Pasadena]

Thanks solidaxel. Exactly the kind of answer I was looking for. I didn't know there WAS a required additive for posi. I haven't even jacked it up to find out if its posi, but I will this weekend. So, 90 wt gear oil AND additive if it is posi and straight 90 wt. without. I think I ended up buying 20w-50 GTX for the engine oil cause I happened to be at Walmart.

Nah, the TH350 is stock as far as i know. Do you think I need to drop the pan for any reason? Or just drain and refill?

[solidaxel]

Is there a 90-140 gear oil?
The additive will most likely come from Ford parts house. The last bit of rear end lube I bought was from Valvoline and some one told me that I didn't need the additive but I bought it just because it wont hurt if is not posi.
If this is the first oil change on the TH350 I think I would replace the gasket and filter and you can se what shape the trans. is in by the amount of "consumibles" in the bottom of the oil pan. The next oil change you can just change the 3 out of 13 quarts in the trans, but this one I would want to know what shape it is in. They always tell you to change the filter with the oil change on the engine and transmission. If you are going to keep it you can never change the oil too much !!!

[Dan in Pasadena]

Okay, so I changed the oil on my '46 today for the first time. Good thing I did because it was BLACK and the moron that put the oil filter in it last time tightened it SO FRIGGIN MUCH I crushed the filter and broke my filter wrench in the process! Anyway, its got a belly full of clean Castrol GTX and a fresh filter now so on to the next thing; flush the coolant and put in fresh, find a billet overflow tank and install it.

[mr48chev]

Some high detergent oils turn black rather quickly but I'd say you were right on to change it.

I've pulled off so many over tightened filters over the years that it isn't an issue anymore. Better than one that leaks though.
For trans fluid I'd use a quality brand Dexron II or III.

As for the rear end it probably takes 80-90 and if it is a posi style unit it needs the additive or gear oil that is designated for posi units.

You may have to pull the cover to drain the rear end anyhow and you can check to see if it is a posi. As Dan in Pasadena said the rear ends are Dana 44's so gaskets are easy to get.

[Dan in Pasadena]

Mr48, Since I know nothing about the history of the truck, do you advise pulling the pan on the tranny for any reason?

Incidentally, if I do pull the tranny pan (and the differential cover for that matter too), what gasket sealer do you recommend? Its been so long since I've done any wrenching other than minor brake jobs and oil changes that I am out of touch. (I've got a feeling this truck is gonna put me BACK in touch REAL soon!)

[hotrodsbyray]

Not trying to be a smart aleck but have you googled for a forum like this for Jag owners? Just wondered since I might worry if the type rear end fluid used would affect seals and such.

[Dan in Pasadena]

That's a good suggestion. Didn't take it as a smart aleck response at all. I doubt a different fluid was used, but it certainly could have been.