Hello,

I just recently purchased a 1960 Cadillac Sedan DeVille (6 window config w/ AC) and have finally had a chance to do some work on it I’m starting with a decent tune up and maintenance on wear items. I have most of the parts I need but I am having trouble finding a few things and wanted to see if anyone else out there may know the answer to a few questions on parts for this year and model.

#1: The rear axle: The car is currently in a place where I cannot lift the back end up to spin the tire to see if it has a limited slip diff or just a standard diff, nor can I get to the ID tag on the rear end to research the model. I believe that Cadillac didn’t offer possi rears until 1964 or 1965. Does anyone know if this is correct or if my year Cadillac has a limited slip or a standard? Also I had called ACDelco for the gear oil in the rear so that I can change it out (I only use OEM parts, I refuse to use aftermarket stuff as much as possible on all my cars) they told me the correct gear oil for that car would be 80W-90. Looking online however there is a 80W-90 GL4 and also a GL5. Does anyone know the difference between them? Does anyone have an idea what GM gear oil would be best for this Cadillac?

#2: The transmission: I have already gotten the filter and oil pan gasket for the transmission but I am having a hard time finding the exact type of ATF that I will need for this car. The service manual I have for the car states that I need an automatic transmission fluid that is a Type “A”. Looking at the specs on GM Dextron VI, it claims to be able to replace all previous GM ATFs such as Dextron III and so on. Could I use VI in this car? Or maybe someone knows exactly what type of GM fluid I would need to get.

#3: Coolant: Same as the transmission, I having trouble figuring out what coolant I can use in this car. Can I use GM Dexcool? If not, any alternatives? Also does anyone know if the coolant to water mixture on this older cadillac differs from the standard 50% coolant 50% water mixture on newer cars? Finally does anyone see any problem with me using a Prestone radiator and block cleaner on this before I put the new coolant in the car? I have used it on my Tahoe and Silverado and it seams to have worked great cleaning out the corrosion at 100k miles but I did’t know if this would harm the older cars.

Any information you can give me would be a great help! Again I am really trying to stay as OEM as possible; GM and ACDelco parts. I have NO problem spending the extra money for the OEM parts, I know in some cases they are almost double but my motto is I’d rather pay for the quality part then buy some cheap part that I will need to change over and over again. Thank you in advance for any help you give!!

Thanks, James!