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Hydra-Matic question


Dan Reed

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I have a 1951 Oldsmobile 98 sedan with it's original hydra-matic. I have the factory 1951 Olds shop manual as well as an original 1946-1955 Hydra-Matic manual. Regarding checking the fluid level - The Oldsmobile shop manual says to check the fluid level with the shift lever in Low. The Hydra-Matic manual say to check with the shift lever in Neutral. Anybody know which is correct?

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Thanks for the replies. Neutral it is. I'm a volunteer at the AACA Library and was able to look through two period Hydra-Matic manuals, which stated check in neutral. Not sure why the Oldsmobile shop manual say check in Lo. That was the confusion. Yesterday was a decent day here in PA so I was able to get the car out on the road and make sure the trans level was topped off. It drove and shifted just fine.

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27 minutes ago, Dan Reed said:

Not sure why the Oldsmobile shop manual say check in Lo.

Ok for the 20th century, but a statement like that would be cause for recalling all the manuals in the 21st century.  

To check the fluid level with the engine running AND in gear makes it a two person procedure. (Gotta have a foot on the brake). 


Attempting it with one person (and who is going to get a helper just to check fluid level?) Is a recipe for being crushed and the source for many lawsuits. 

That procedure would never get past the legal department today 

Edited by m-mman (see edit history)
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17 hours ago, m-mman said:

Ok for the 20th century, but a statement like that would be cause for recalling all the manuals in the 21st century.  

To check the fluid level with the engine running AND in gear makes it a two person procedure. (Gotta have a foot on the brake). 


Attempting it with one person (and who is going to get a helper just to check fluid level?) Is a recipe for being crushed and the source for many lawsuits. 

That procedure would never get past the legal department today 

Not necessarily too dangerous for one person with the old floor fill/check hydromatics. The filler opening and fluid check was on the left top of the transmission and accessed through a hole in the floor. OOPS! filler is on the right side top.

Edited by hook
correction (see edit history)
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Yeah, I don't think that would fly today (checking the fluid with it in any gear). The manual tells you to block the front wheels (they show a rather large metal wheel chock) and apply the parking break. Yep, the dip stick is located under a pop-off plate on the right side of the trans hump.

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