Packard Forum Index » Post-War (1946-54)

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Considering that the units can be adjusted satisfactorily with Type F, I'm not sure what benefit there would be with something more expensive. The main thing that would help past that is viscosity or film thickness modifiers that would work at high temperatures to boost the film thickness in the bushings and washers. But again, mainly a concern at high temperatures from aggressive acceleration.

I love the oil conversations, always lots of opinions and controversy!

I have been running Pennzoil Type F in my 53 Cavalier's Ultramatic for the following reasons.

1. It does not contain friction modifiers, which the Ultramatics were not designed for, and do not always like. I think poor direct drive clutch engagement/slippage is the most common issue when using ATF with friction modifiers. I don't suspect there would be any notable issues with the low range or reverse bands.

2. It is designed for a temperature range of 175-225 F, which should be just right for our cars.....if operating correctly. (Pennzoil Type F does contain viscosity modifiers.) One thing I do not know is how the viscosity of Type F compares to the viscosity of the oil originally used, and that the Ultramatic was designed for. I suspect the viscosity could affect the torque converter efficiency, but once the direct drive is locked up this should be irrelevant.

3. Pennzoil Type F is readily available from NAPA or Walmart. Not a good reason to use it, but a reason.

In terms of lubrication, I would think that any modern ATF would run circles around an ATF from the 50's. Having said that, how the ATF interacts with the metallurgy of the Ultramatic's components would be a consideration. But again, this would require laboratory testing to determine.

I would not use an oil additive in my motor or transmission oil. The reason being is manufacturers go to great lengths to design and test their oil's formulations. When an additive is added there is no way of knowing, outside of laboratory testing, how the chemicals in the additive will react to the chemicals in the oil. Russian roulette!

PGH, I'll be disappointed if you don't respond!

Transmission fluids need to do a lot of things. They need to be appropriate for spur gears as well as yellow metals. They need to work well with clutches to provide smooth engagement without slippage. The transmission fluid heats in the converter, so they need to maintain sufficient viscosity. They enjoy not having to deal with crankcase vapors, but on the other hand don't get hot enough in the sump to evaporate water well should it enter from condensation.

Journal bearings are used such that under normal operating conditions they will provide hydrodynamic lubrication. This means that the film of fluid that is dragged under the rotating shaft is thick enough to positively support the shaft. Tighter clearance, higher viscosity, lower bearing pressure (load), and faster turning speed will engender hydrodynamic lubrication. Neither the shaft nor bearing will experience wear during normal running. Therefore, the main assistance provided by formulation is with viscosity modifiers to keep the fluid from thinning out. The bearing fluid temperature is somewhat higher than the overall converter temperature as the bearings make a significant amount of heat so the transmission fluid must be suitable to a higher actual temperature than the converter temperature.

It may be noted that the thrust washers used do not provide hydrodynamic lubrication, but instead boundary lubrication. In practice they seem to not wear much faster than the journal bearings, though.

Given all this, which should be handled well by nearly any fluid of a standard viscosity, the question falls generally on the clutch behavior, which is why we use Type F.

PGH, makes sense to me!

My biggest issue is keeping my Type F inside my Ultramatic! The gear shift shaft seal leaks, which I replaced once, but I think the shaft needs to be cleaned up. One day I'll get to that.

Did you check whether it's actually leaking past the shaft (you would see that) or just leaking past the bore? I would think bore more likely as if someone scored it in the past then it will keep wanting to leak.

I think it's the shaft that got scored at some point.