Correction- through ignorance I mis-stated something to John E and all

[jetcone]

and I'd like to correct that here. John E and I have been having a running debate on what fluid to use inside the Bendix trannys. This actually affects all of us here. I did some learning this week and found out I was not quite correct so here is the skinny!

 

John swears by Automatic tranny fluid and I want to say he is correct in that, contrary to what I had been saying! Auto tranny fluid is safe for Bronze and Copper elements. These are what make up the bulk of bearings in vintage transmissions from washers to tractors.

 

I had always said 90 weight hypoid gear oil is all you should use. I was in error there as there are 5 different grades of gear oil GL1-GL5. You have to check with the manufacturer to see if they are compatible with bronze or "yellow metals". GL1 usually is. And now GL5 is mostly compatible. I use Royal Purple gear oil now as it states its compatible with yellow metals.

 

BUT John was right in using AutoTranny fluid as well. I was wrong in saying that wasn't good to use.

 

We all live and learn our hobby.

Here is a rebuilt motor filled with Royal Purple and going back into my 1956 Gyromatic for another 54 years of service. Enjoy!

 

[gansky1]

The bottle of 85W Rotella's Gear Oil that I used says compatible with GL-5 and also hypoid gears.    Should be OK?

 

 

 

[tomturbomatic]

I never changed the tranny fluid in Brenda, my Duomatic, but she was never as loud in the spin portion of the cycle as that machine was in the museum last fall. You would not even be able to use that in a multi-family dwelling.

 

[jetcone]

Greg it depends

you'll have to check the manufacturer, the EP =extra pressure additives they add can eat away at the yellow metals. Later I'll check their site for compatibility.

 

 

[supersuds]

Isn't there quite a difference in viscosity between ATF and SAE 90 gear oil?

 

[hydralique]

"EP =extra pressure additives they add can eat away at the yellow metals"

 

This is quite true, EP should be avoided in applications that don't need it. Generally it is only required when hypoid or bevel gears are used.  Before the '80s cars with transverse engines and gearboxes (which do not use bevel gears) were fairly rare in the US and non-hypoid gear oil was also quite rare, so commonly available EP oil got poured into these transmissions, some of which had synchro rings that were destroyed after a few years exposure to the EP additives. My first Fiat X1/9 was bought very cheaply at six years old with 50K on the clock with a synchro so bad it required replacement of both the gear and sycnchro ring and associated sliding sleeve. My later X1/9 was never filled with EP additives and still had a perfect gearbox when I sold it even with over 180,000 miles in LA traffic. Fiat and other affected manufacturers of course got the blame for bad gearboxes, even though the owner's manual and all factory manuals clearly stated "No EP Additives". The scary thing about these kinds of incompatibilities is that the damage isn't instant and you can't hear it happening, but after a few years of exposure the yellow metals simply dissolve and then stuff fails to work.

 

One substitute for gear lube without EP is single weight mineral oil such as motor oil meant for very old cars that don't do well with modern detergent additives - you won't find these at the local parts store but they're available online. Remember that the viscosity ratings for gear lube and motor oil are different, with a 90 weight gear oil having about the same viscosity as a 40 or 50 weight motor oil. Another good gear lube is Redline synthetic MTL or MT-1. Neither of these has EP, with the MTL being fairly lightweight (more like ATF) and the MT-1 being similar to 75w90; both however are modern synthetic formulas that may or may not be happy in an old appliance. I'd be tempted to go with the single weight non-detergent mineral motor oil because it has fewer additives that aren't needed in appliances, and it is available in a wide variety of weights ranging from lightweights similar to ATF to the heavier 40 and 50 weights.

[this post was last edited: 5/27/2011-19:12]

 

[qsd-dan]

Yeah, be sure to use GL-4 oils if there's any possibility of yellow metals involved. I use Redline MT-90 (75w-90w) in manual transmissions that require 80-90 weight oil. It's a synthetic GL-4 oil, but isn't too slippery like most other synthetic gear oils, which can actually cause grinding during shifts. Works wonders, especially during very cold mornings.

 

[jetcone]

Dan

<span style="white-space: pre;"> </span>I'd question that GL-4 oil, its the Gl-2-4's that usually have the EP additives in them from what I've  seen so far. From what I read this week I think the GL-5 is reserved for all synthetic oils and the syn's don't need the EP additives they are so slippery.

 

 

[qsd-dan]

GL-5 is reserved for all synthetic oils and the syn's don't need the EP additives they are so slippery.

Yeah, but most GL-5 oils contain reactive sulfurs, which will eat away at yellow metals From what I've seen, GL-4 oils designed strictly for manual transmission don't have the EP additives. GL-4 oils that claim to be "multi-use" for applications like differentials, among other uses that contain hypoid gears, usually DO have the EP additives.

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

 

[jetcone]

Greg check with Shell directly

Your Rotella gear oil states: <span style="font-family: Helvetica; font-weight: normal; font-size: 10px;">Contains a sulfur/phosphorus additive system</span>

for excellent load Carrying capacity" on their website.

<span style="color: #888888;"><span style="font-size: medium;">Their website says it has EP additives in it.</span></span>

http://aglayne.com/wp-content/uploads/2010/11/Rotella-HD-gear-oil-80w90.pdf

 

[dnastrau]

Oil questions

Just my two cents on oils based on my experience...

I had several VW cars that required GL4 oils. Oils that met both GL4 and GL5 were a no-no in that application due to the damage that the GL5 additives caused to yellow metals. I used Redline MTL (a thinner version of Redline MT-90) with great results. Redline MTL might work well in the Bendix gearbox as it is not too thick and is GL4 only.

I would not use Rotella in the Bendix transmission as it is a GL5 oil.

 

[jetcone]

Andrew

thanks for the info, its good to have alternates! I have stocked up on Royal Purple right now but will keep my eye out for Redline MTL too. The price is right!

 

jon