PD 4104 transmission oil

[richardkillmon]

My father-in-law has a 1958 PD 4104 which has a 4 speed manual transmission and
put 90 wt. oil in the transmission box in the rear near the motor. He says that the oil now bubbles or has
bubbles in it, what could cause this? What wt. oil should go in the transmission?
rkillmon rang the bell

[roadrunnertex]

PD-4104 transmissions use the same oil that you put in the engine.
Do not use 90wt transmission oil.

[usbusin]

Use 40 weight oil.  Not, transmission oil or multi-weight.

[gus]

The 4104 manual says use 50W "Aircraft Oil" which in those days was straight mineral oil.

I use 50W aircraft engine break-in oil which is the same thing. You can find it at any airport but the price is ridiculous.

I just happened to have mine because a buddy bought the wrong oil for me, don't know yet what I will do when I run out!!

As already posted, DO NOT use 90W gear oil or any other heavy oil. The reason is that the 4104 trans has an oil pump, not many - if any - manual transmissions have oil pumps. My guess is that the pump was supposed to improve cooling since it circulated the oil better. That is only a guess.

Gear oil is too heavy for the pumps.  In real cold weather it would probably break a pump. It was a trans that GMC trucks used in the old days and probably many others also since it is a Spicer trans. I happen to have a couple of big GMC oldtimers which is the only reason I know about them.

[Dallas]

Interesting answers....

But... If I remember correctly, The SAE viscosity rating for motor oil and gear grease are two completely different things.

The viscosity for motor oil at 40-50 is essentially the same as the viscosity of gear grease of 90.

As an example, I'll post the AMSOIL piece on this subject, except I ask you to please remember, I have never been a big believer in Amsoil products, or most other snake oil, except for that which I sell on any given day.

I'm too tired right now to look up any other references, but you, dear reader, should be able to handle that little task all on your own.

(Sorry, I forgot to post the link)
http://www.amsoil.com/articlespr/2007/article_GearOilBasics.aspx

Dallas

[johns4104]

Seems like I remember reading some where that a multi weight gear lube 80w90 is about the thickness of the straight 50 weight oil.

Does anyone else know?

Thanks,
John

[Dallas]

John,
See:
http://www.amsoil.com/articlespr/2007/article_GearOilBasics.aspx

Seems like I remember reading some where that a multi weight gear lube 80w90 is about the thickness of the straight 50 weight oil.

Does anyone else know?

Thanks,
John

[richardkillmon]

As always, you guys are the best. It is nice to know that I have a life saver. Thanks
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thanks   thanks thanks   thanks thanks   thanks thanks   thanks thanks   thanks
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[gus]

Dallas,

That article was a revelation to me because I just assumed the viscosities were the same for all oil!!

So, this new knowledge tells me that 90W gear oil is fine for my 4104. This is good news because the 90W cost is probably 1/10 the cost of aviation mineral oil and I am almost out of my original supply.

It also tells me that something other than GL-5 gear oil (Probably GL-1) is correct for the trans because aviation engine mineral oil is not extreme pressure oil by any definition. The only XP oil called for in the 4104 is for the steering box?? I'm not sure I understand that, especially since the differential does not require XP oil?

However, I have an antique White WC-22 truck tractor which has a much heavier duty diff and it also does not use XP gear oil even though it requires 140W? It seems logical to me that diffs would all require XP oil but that is not the case. This diff is a monster too even though it is ancient.

[Dallas]

Here's a bit more information if you want it, although the font on the page is a bit hard to read:

http://www.jwmercantile.com/infooil.html

And this one from "Bob is the Oil Guy", not to be confused with "Smiling Bob", who has a different use for oil.

http://www.bobistheoilguy.com/visc.html

IHTH,

Dallas

[steve5B]

  I WOULD LIKE TO MENTION, ( THERE ISN'T A "WEIGHT" OF OIL. THE "W" STANDS FOR (WINTER) VISCOSITY IS MEASURED IN

  S.U.S  THIS MEANS, SABOLT UNIVERSAL SECONDS.

   JUST MY 2CENTS WORTH!

    STEVE 5B........

[zubzub]

FWIW there is a 50 W oil at NAPA that is for motorcycle racing. When I needed oil for my spicer , I looked up the specs in the manual, and the 50w oil at napa matched the specs., don't have my manual here so can't remember exactly ...anyway the oil wasn't cheap but it wasn't crazy.  I read the Amsoil link and it didn't really make me want to use 90 gear oil in my tranny maybe I'm missing something?

[JohnEd]

Synthetic lubes better than Dino but it is also "thinner".  Seems a contradiction but there you are.  Their 90 might be thin enuff but take this to the bank.....they support a very fine product and want no truck with having it CAUSE a failure.  Using Syn in you trans and diff and engine will bump up your MPG and protect things better.  I once heard that if you need 30 WT oil in your crankcase you could use 20 wt Syn and get the same protection and less resistance.....for the win.

Hard for me to disagree with Dallas and take that to the bank.  I have poured a lot of 50wt oil in my time and I have also poured, if you can call it that, a goodly amy of 90 wt gear lube, sometimes called "grease".  The 90 has been lots thicker than the oil ever hoped to be, at least from my recollection.  90 wt Syn seems closer to 20 wt and I did that last month.

FWIW,

John

[WEC4104]

I recall some discussions on this same topic from 2-3 years ago.  At the time, some folks were stating that they had switched from using straight 40W to a synthetic 50W.  They were reporting it made the Spicer much easier to shift.  There was a caution tacked onto those comments, however.  The synthetic was more prone to leak through worn seals, so it was not recommended for Spicers without first checking or replacing the seals. 

My Spicer only barely holds the conventional 40W (most of it at least), so I haven't tried the synthetic.

[Dallas]

At one of the other links I posted is a piece on Synthetic vs: Dino gear oil. It's an interesting bit of reading.

http://www.bobistheoilguy.com/gearoiltest.htm

You may also be interested in the rest of the website also:

http://www.bobistheoilguy.com

However, even though the site states that they don't sell or recommend any oil, they are constantly referring to Schaeffer's brand, which I admit is good oil, but leads me to believe the site could be an advertisement for Schaeffer's, in disguise.

Dallas