Re: '39 Packard 110 Transmission Fluid (& Rear Dif Fluid)

Posted by Tim Cole On 2010/7/6 18:28:39

I've done a lot of inquiries on this topic with oil companies and such.

The general reason many European makers specify 10w-40, or straight 40, for transmissions in the lack of EP.

Nissan specifies GL-4 which has less EP than GL-5. Your standard 85w-140 is GL-5 (gear lube).

However there is a military spec (ML2105 I think) that specifically requires GL-5 to be non-reactive toward bronze.

The modern EP is nowhere near the old stuff which was totally hazmat. I drained the trans in a 37 V-12 that was junked in 1956 and it had EP in it.

Things get more wierd because many GL-4 oils (if you can find them) are often just GL-5 with a different label.

Packard specifically warned that using heavy gear greases (250,600w) will damage the EP surfaces due to oil starvation. Many show cars have this stuff in them to reduce leaking and this is safe for trailers.

Bendix said no to EP in the overdrive.

A survey of later American cars shows EP sanctioned for manual transmissions from 1954 onward. Generally the reactive issue exists only at the high temperatures that occur on EP surfaces. Synchros don't get hot enough unless they are being speed shifted.

My experience is that 85w-140 produces notchier shifter feel in column shift Packards with better synchro action.

However in column shift Packards, I am now using a 50-50 Lubriplate mineral oil 140w, 85-140 GL-5 mix to please Bendix, produce authentic shifter feel, and provide the corrosion protection you get with a modern oil. This mix used to be called mild EP or GL-3.

Alot of the synchros in these old cars are shot and can't be speed shifted like when they were new. I don't know what the oil might have contributed to this result.

Avoid putting heavy greases into anything without first consulting factory literature.

Lubriplate 140w can be had through Restoration Supply and is a little pricey.