Packard Forum Index » Pre-War (1899-1942)

Hi All,

I've been reading a lot of conflicting info on the use of GL-5 in classic vehicles.

Is 85-140 EP GL-5 an appropriate choice of Gear Oil for Transmission. overdrive, rear end and Steering gear in my 1941 1901?

This is the product I am considering: Valvoline High Performance Gear Oil

Thanks,
Chad

I've used that same product for decades in the standard trans, differential, steering gear and rear axle of my 34 Packard, my 48 Custom 8 and also in my 56 Caribbean steering gear and rear axle; never a problem. I've also used it in a 1941 180 rear axle and trans a few years back.

There was a problem with early extreme pressure hypoid gear oils back in the late 20s and 30s (maybe into the 40s) that used a sulfo-chloro lead compound as an EP additive which could attack "yellow metals" such as synchronizer rings and/or bronze bushings but apparently that problem was overcome years ago. Based on my long-term experience you should have no problems attributable to that gear oil, I think it's a good choice.

Thanks OD for the explanation, and clue as to what to look for regarding so much confusion about EP.

I think the 4th or 5th paragraph in this article sheds some light the reason for confusion regarding the issue of EP additives: EP Additives

"The early EP additives were based on lead salts of fatty acids ("lead soaps"), "active sulfur" compounds (e.g. thiols and elementary sulfur), and chlorinated compounds. During the 1950s the use of lead soaps was eliminated and replaced by zinc and phosphorus compounds such as Zinc dithiophosphate.[2]"

And the very last paragraph.

"Sulfur containing EP additives can cause corrosion problems in gears with parts made of bronze, brass and other copper alloys when high temperature environment is encountered."

Thanks,
CG

Thanks for putting an approximate date on the changeover, and nice to hear that my memory was correct on the chemical type of additives used. The older EP gear oils with the sulfo-chloro lead additives were pretty easy to identify with your nose - they had a very characteristic pungent (and unpleasant) odor. I used one of those products (a Pennzoil product) in the differential of my 34 back in the 60s, later flushed it out and replaced it with GL5 when I first became aware that it was on the market.

I drained and refilled the rear end about a month ago. Easy enough to do.

I finally got around to a drain and refill on the transmission and overdrive yesterday. Also a simple and straightforward procedure.

Only 1/2 quart total between the Trans and OD is all that drained out. I refilled the Econo-Drive 1st (with Transmission fill plug removed), and then the Transmission. The 2 units took about 1.5 to 1.75 qts together. Clearly maintenance was overdue.

This leads me to a followup question regarding the the diagram in the owners manual; The Diagram on page 15 of the 1941 One-Ten/One-Twenty Owners Manual shows the transmission fill plug at about a 45 degree angle, as in the attached picture. Mine is straight in. Is that significant in any way, or just a discrepancy between the drawing, and how the transmissions were made?

Thanks again,
Chad

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