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59 Cadillac fluid question

Started by chris92026, January 21, 2018, 12:34:24 PM

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chris92026

I have some question about fluid to use on a 59 Cadillac Sedan Deville
for a driver
coolant what do you guys use?
power steering ATF or power steering fluid ??
automatic transmission what kind of fluid ??
brake fluid ??

thank you
C.Perrin

TJ Hopland

Coolant I think a vast majority of people just use the classic green stuff and changing it as recommended based on either age or miles which ever comes first.   Exception would be the few that believe in something that most would consider 'exotic' like say Evans or the 'red' stuff that apparently has become the norm for heavy equipment.  Very few classic folks seem to use the extended life stuff such as Dexcool.    I would either buy the 50/50 or pick up distilled water and mix it.   Unknown water quality isn't work the risk of corrosion.   For a driver adding an expansion / overflow tank can keep things a little more stable. 

PS and ATF are very similar fluids and the older stuff doesn't seem to be that sensitive like stuff say from the 90's on can be.   I have been using PS because of the different color, its easier to know what is leaking if all the fluids are a different color.    I even put the special blue fluid in my truck transfer cases that don't require it just for the different color.   Apparently blue was supposed to be a standard color for synthetic ATF sorts of fluids but it didn't really catch on. 

Trans unless its been rebuilt and the builder has a specific recommendation I think the what is now sold as universal Dex-Merc is the most commonly used.   Its supposed to be Dexron 3 but is no longer certified by GM so in theory no guarantee what you are actually getting.  I think Dex 6 is the only currently certified one you can get and GM claims its backward comparable all the way back to the original Dexron fluid.    There seems to be great debate if its really good to use in 'old' stuff.   The shops I have dealt with (too frequently lately) all say 6 only goes in stuff that came with it from the factory, rest get the dex-merc stuff.   Maybe that is to keep people like me coming back for rebuilds? 

Brake fluid the options are pretty much 2 groups.   Dot 5 and then 3,4,5.1.   Dot 5 is the one that doesn't mix or play nice with the others.  They way to tell what you have is get a sample and mix some water in it.   The dot 5 won't mix with the water the others will mix and make it kinda cloudy assuming it was clean to begin with.  If you have 5 you might as well stick with it.  Same thing if you have one of the others.   The time to change is with a total system rebuild and flush.   For a street driving car I don't think there are real performance differences.   Some like the idea of 5 because its not as hard on paint and doesn't absorb moisture so I suppose in theory extended life.   My thinking is if you have constant issues with brake fluid on paint you have bigger problems with your system.  As for the moisture if you change it every couple of years I don't think its a big deal.   I bet down south (out of the rust belt that forces fluid and component changes) there are lots 10-20 year old cars running around on factory dot 3 brake fluid.  40 years ago hoses didn't last 10 years but now they do.   Its just not something most people thing about and must not be that much money in it so the quick change shops don't push it.       
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

David Greenburg

I would stick with the “classic green” if you’ve got a copper core radiator. The newer stuff, designed for aluminum, can attack solder and lead to leaks.
David Greenburg
'60 Eldorado Seville
'61 Fleetwood Sixty Special

chris92026

thank you, i will go with your recommendation
C.Perrin

INTMD8

I don't have a strong preference on most of it but I do prefer Dex 6 in the trans

DylanFan52

With apologies to Chris for hijacking this conversation I would like to ask a followup question to TJ.  I am in the process of having my 1959 Cadillac Hyrdramatic completely rebuilt. I think the fellow rebuilding it is in over his head so I do not think I can rely solely on his recommendation on what type of transmission fluid to use if I ever get it back on the road.  Assuming I will get it running would Dex-Merc be the correct fluid?  Thanks!

CadillacRob

Just had my 56 hydramatic rebuilt by a very knowledgeable guy and he was adamant that I only use dexron 3.  Said it's available online
1950 series 61 sedan
1956 coupe de ville

TJ Hopland

'In over his head' is a bad sign with those (or any) transmission.  There is apparently several aspects of those that are not like newer models.   When I was shopping for a place to have one done a couple years ago I found several that just said no.  The couple I found that would do em would not do them carry in,  they required the whole car.   I ended up at a shop I had used before and they will do carry in on things like a c3 or 350 so that tells me that those can just be set on the bench and are likely good to go but these take a lot of tweaking and testing that can only be done in the car. 

What I have been told is the fluid choice has to do with the clutch materials.  Earlier materials either worked or lasted so they needed specific additives in fluid to get the other aspect.  Ford's were an example of a material that was apparently pretty tough but it didn't grip very well so they had something in the type F that helped with that.  That was why if you had a GM trans that was starting to slip you would dump some type F on it then sell it.  Eventually the aftermarket catches up to the OE's and upgrades the materials for the old models so that is when you can upgrade to the more modern fluid.   

Is 6 pretty much just a synthetic 3?   It might be.  As a gear lube I think synthetics are great.  On clutches I don't know.  Like I said above it could just be a conspiracy by the shops to keep us coming back. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

wbdeford

I use Dexron III in my 58 transmission and power steering.

For the cooling system, I use distilled water + water pump lube/anti-rust + denatured alcohol.  Since I don't drive it much in the winter, I don't lose much alcohol to evaporation

In warm seasons, I leave out the denatured alcohol. 

I started doing this because I was noticing coolant loss that I couldn't account for and I couldn't rule out the possibility it was getting in my crankcase.  Since the cutover, I have never had to add to the cooling system between refills.
1958 Sedan de Ville

Past:
1956 Fleetwood 75 Sedan
1957 Fleetwood 60 Special
1958 Miller-Meteor Futura Landau Duplex
1960 Coupe de Ville
1966 De Ville Convertible
1970 De Ville Convertible
1971 Eldorado Convertible
1979 Sedan de Ville
1980 Seville

CadillacRob

I run dexron VI in my 1950 Cadillac without problem.  It's a full synthetic.  My transmission guy urged me to only use dexron III in the one he rebuilt for my 56.  Said 6 is too slippery
1950 series 61 sedan
1956 coupe de ville

Dave Shepherd

Great article in the latest Car Craft referring to trans fluid and their recommended applications, Dex V1 seems to not be the one to use on older transmissions. Dex/ Merc, yes.