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I know the idea of modern gear lube, yellow metals (brass/bronze), and correct gear lube weight has been flogged to death.

I am particularly interested as it relates to my '29 626. Is there any yellow metal (brass or bronze) used in bushings, thrust washers, or spacers in the transmission or differential? I realize I do not have synchros, so there is little risk with using a GL-5 Gear Oil. Modern GL-5 gear oil is supposedly non-corrosive to brass or bronze. Corrosion is not the problem.

Information I received in an e-mail from Richard Widmer (http://www.widman.biz/Corvair/English/Links/Transaxle.html) explained "As for the GL-4/GL-5 issue, the GL-5 covers and surpasses the GL-4 ONLY in EP protection. They are not the same and are not interchangable. Most gears oils of 40 years ago had lead based EP packages. Today they are Sulfur/Phosphorous. The GL-5 has twice the sulfur/phos quantity as the GL-4. Sulfur/phos works by chemically forming a sacrificial surface on the surface it is to protect. That (black) covering wears off and forms again to wear off and form again. On steel that is fine. On soft metal (brass, etc) it peels off a layer of the soft metal. Not really visible to the eye (that can only see >40 microns) but shows up as worn area over time or in oil analysis. So if a differential or transmission has brass or other soft metals (synchronizers, forks, or shims) you probably want to stay away from GL-5. If it is all steel, GL-5 is fine and will provide better anti-wear."

So, is there any brass/bronze in my '29 Packard?

Thanks for your help.
Pat

Dear Pat:

You do not have to worry about EP additives in your transmission. It is all steel.

However, the unit requires SAE 160w summer and 90w winter. Some people put 250w in them, but Packard warned against too heavy an oil - especially in winter.

I don't know how 85w-140 performs, but you can get 160w from Lubriplate or PittPenn.

For the case of Synchro transmissions, I tested copper in GL-5 and found that it did react. However, I usually found that most of those transmissions were running for years with EP in the transmissions so whatever damage was to be done had already occurred. For cases of shot synchros the GL-5 seemed to improve shifting, but the synchro transmissions are all living on borrowed time which is why I like the non-synchro series Packards best.

Also, modern EP is less reactive than the old stuff, but a call to Mobil found they concurred that GL-5 is still reactive. The Military spec for GL-5 being bronze tolerant notwithstanding.

Thanks Tim for your help,

I have been using 140w GL-4 in the trans and diff.

I raised the issue because I just noticed that the Service Manual calls for "600W or Whitmore's 'O' Compound". Is 160w the new 600w?

I know the higher viscosity will aid in shifting (although we really do not have a problem). The transmission and differential depend on "splash" lubrication as the fill level is below the bearings for the transmission input and output shafts. With the higher viscosity it could take a bit to get gear lube to the bearing surfaces, particularly if the car sits for any length of time.

Our winters are very mild, rarely getting below 32 degrees, and this car winters in an Airplane/Automobile Museum.

We are preparing to take off on the CCCA National Tour in a few weeks, and we think we will be the oldest car on the tour. That means that we will have to "push" the car a little more than normal (note, I said push, not thrash).

The added protection of the GL-5 in both the trans and especially the differential would be welcomed; if for no other reason than to put us at ease.

Thanks again,
Pat