55 Transmission Oil

[Fenwick B.]

I have put about 600 miles on my 55 since I have had the transmission and engine rebuilt, and I have just changed the Mobil1 oil in the engine for the second time. The oil did not have any metal visible, and I couldn't pick up anything with a magnet, so I think that it's Ok. The transmission was rebuilt about 2002, but I didn't put oil in it until 2007. I have been running the car since then, and I have never changed the transmission oil. The car runs good, but I was wondering if I should change it, and what type of oil I should use if I do change it? Fenwick

[Larry M.]

Re: 55 Transmission Oil

Fenwick:

What transmission are you running in the car? A PG or 3-speed?

What viscosity Mobil 1 are you running and do you know the ZDDP level? You may want to consider an oil with a higher ZDDP level or add a supplement. Mobil 1 website lists each oil and their specifications, zinc levels, etc.

If you have a PG, you can still get the old Type A fluid, but I believe the current DEXRON fluids will also work okay. If a 3-speed, GM sells an 80-90W fluid that should work for you. I can get the part number if needed. What are you using now?

Larry

[Fenwick B.]

Re: 55 Transmission Oil

Larry, it's a powerglide two speed, and i'm using Dextron in it. I am using Mobil1 10W30 in the engine.

[Duke W.]

Re: 55 Transmission Oil

Mobil 1 is an API SM oil designed for modern engines. Vintage engines are better served with a CJ-4 or CI-4 oil

Duke

[Fenwick B.]

Re: 55 Transmission Oil

Thanks Duke, I will do that next oil change. Do you think the initial transmission oil should be changed with so few miles on it?

[Roy B.]

Re: 55 Transmission Oil

No as longe as it's RED in color

[Duke W.]

Re: 55 Transmission Oil

Thanks Duke, I will do that next oil change. Do you think the initial transmission oil should be changed with so few miles on it?

I'm not that familiar with the old Powerglides, so I have to defer to those who have experience with them, but I would think that the current Dexron is okay.

As far as changing, you should first look at GM's recommendation for that era. I recall in the seventies the TurboHydramatic recommended service interval was 30K miles and it included changing the internal filter, but I don't know what the recommended service interval was in 1955 or whether the PG has an internal filter.

Since today's ATFs are formulated from much more oxidation resistant blends of base oils than what was available when they were new, the OE recommended service interval should be more than adequate.

The modern synthetic friction modifier to prevent wet clutch chatter (as is the case with Positraction axles) is also a lot more durable than the whale oil derived additive used in the old Type A Suffix A ATF from the fifties.

With time the transmission fluid slowly oxidizes with heat and turns brownish or even black if it's really old and oxidized.

Duke

[Larry M.]

Re: 55 Transmission Oil

Fenwick:

I wouldn't worry about the PG. I believe that they have a filter/screen that should remove any debris. If you experience shifting issues, THEN I would pull the pan and check the filter and replace the fluid. With your annual miles, that fluid will last a lifetime

About the engine oil, I have a case of 15W-40 CI-4 oil that I bought (overbought) a few years ago. I have more than enough for myself for years to come, so you are welcome to the case. Will deliver to next Chapter meet if you want. Otherwise, get some Shell Rotella. You can even get 10W-30 if you are willing to search a bit. Otherwise 15W-40 is fine for Louisiana year-around.

Larry

[Bert L.]

Re: 55 Transmission Oil

Interesting gizmo Roy, never seen one like it before. Hope it never decides to spring a leak into your lap!
"Keep 'em coming"

Best regards,

[Duke W.]

Re: 55 Transmission Oil

Fenwick:

Otherwise, get some Shell Rotella. Otherwise 15W-40 is fine for Louisiana year-around.

Larry

There are plenty of other brands. Any big box or auto parts store has a section of C-category oil. I buy on price.

The commonly available 15W-40 is okay for cold starts down to about 10-15 degrees F, which should meet the needs of most owners who don't drive their vintage cars in the dead of winter. It's also suitable for triple digit temperatures where most of us will park our vintage Corvettes and opt for modern air-conditioned wheels.

Duke

[Roy B.]

Re: 55 Transmission Oil

Interesting gizmo Roy, never seen one like it before. Hope it never decides to spring a leak into your lap!
"Keep 'em coming"

Best regards,

I've shown it before but people still have never seen one.Have had it in my 55 for years
You need it in your 60PG

[Mike M.]

Re: 55 Transmission Oil

Fenwick:

I wouldn't worry about the PG. I believe that they have a filter/screen that should remove any debris. If you experience shifting issues, THEN I would pull the pan and check the filter and replace the fluid. With your annual miles, that fluid will last a lifetime

About the engine oil, I have a case of 15W-40 CI-4 oil that I bought (overbought) a few years ago. I have more than enough for myself for years to come, so you are welcome to the case. Will deliver to next Chapter meet if you want. Otherwise, get some Shell Rotella. You can even get 10W-30 if you are willing to search a bit. Otherwise 15W-40 is fine for Louisiana year-around.

Larry

no tranny pan on a cast iron powerglide. mike

[Larry M.]

Re: 55 Transmission Oil

There are plenty of other brands. Any big box or auto parts store has a section of C-category oil. I buy on price.

The commonly available 15W-40 is okay for cold starts down to about 10-15 degrees F, which should meet the needs of most owners who don't drive their vintage cars in the dead of winter. It's also suitable for triple digit temperatures where most of us will park our vintage Corvettes and opt for modern air-conditioned wheels.

Duke

Duke:

I agree. But down here on the bayou, Shell is a local brand/icon...and Fenwick is an old pipeline supervisor.

Larry

[Larry M.]

Re: 55 Transmission Oil

no tranny pan on a cast iron powerglide. mike

Mike:

Thanks for the education. I learned on F*rd auto transmissions beginning in the early 60's. Didn't jump ship to Chevies until the 70's. Made a bad assumption.

Larry