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

Hello, looking for any help or suggestions in regards to oil weights for the transmission, rear axle, and gearbox on a 1940 Packard 120 1801 series. Any help would be grealty appreciated.

In my formerly owned 115C I used 15W-40 Classic Car oil in the engine (bought it from Classic Car Club of America). 85W-140 GL-l gear oil in the transmission and 85W-140 GL-5 gear oil in the differential. Actually, any 10W-30 engine oil will work too. Make sure the differential oil is GL-5 rated. GL-1 for the transmission is needed in the transmission and overdrive.

P.S. Don't worry about having to use high Zinc content motor oil. These straight eight Packard engines don't need it.

Thanks JWL. This project has been quite the learning experience. Any information I can get my hands on is greatly appreciated. Engine was rebuilt many years ago and paperwork requests use of 10w30. No mention of the high zinc stuff. Why would it not be required? Considering the age of the engine itself.

The zinc additive is designed for certain later model high performance engines with non-roller camshafts. These engines were manufuctured in the late 1950s though about 1972.

Older engines that run at lower speeds with much lower valve train stress have no need for the additive and using it will offer no advantage.

Any good quality multigrade oil will give good results in old Packards.

A 10W30 is excellent for general service in most areas. A 10W40 or 15W40 are good options in hot weather areas, and engines with high mileage can benefit from using 20W50 in hot weather.

I've had good results using full synthetic oil in a Model T Ford that I drive a lot in hot weather at 40+ MPH, which is fast for a T.

I see no reason why it would not give good results in an old Packard.


Packard would have recommended multi-grade oil for pre-war Packards, if it had been available.

I would not run any motor oil in a pre WWII engine for more than 4,000 miles.

I see no need to change modern oil in an old engine that is clean and in good condition at very frequent intervals unless it is driven under extremely adverse conditions.


In this area, non-synthetic motor oil is becoming scarce, and the price difference between synthetic and non-syntheitic has narrowed a lot.

I liked Wal Mart's 20W50 conventional oil for old engines, but it seems to no longer be available in this area.

Zinc dialkyldithiophosphate received a patent in 1944, and has been an additive since. Your engine has had a steady dose for close to 80 years. I would recommend it's continued use. Engines that are manufactured with steel roller tappet camshafts do not require ZDDP.

fourbybud,
to PackardInfo.

I invite you to include your '40 120 Packard in PackardInfo's Packard Vehicle Registry

I will. I promise. Lol

I have mostly used Amsoil my entire life. Not wanting to start any heated debates, but what's everyone's opinion on using 75w140 in everything?

GL-5 is recommended for diff, while GL-1 is recommended for transmission. Different animals as far as additive packages.

Agree about the GL1 and GL5 differences but are they not backward compatible? I have verified that the Amsoil is "yellow" metal compatible. And I have not found GL1 oils very obtainable.