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rotorwrench · 12-25-2020, 10:05 AM

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I would caution folks to make sure the shocks are empty of any previous fluid before attempting to change fluids. The old glycerin based and castor oil based fluids are not compatible with mineral oils.

I would gravitate toward an hydraulic oil with a viscosity that is near SAE 50 motor oil. SAE-50 motor oil is the same viscosity as SAE-90 gear oil but without the sulfuric acid/phosphoric acid based extreme pressure additives. A person may need a conversiion table for the difference between the ISO viscosity grading system and the SAE system since most hydraulic oils are now graded on the new international system. ISO-150 is very near SAE-40 and ISO-220 is very near SAE-50. Hydraulic oils would be the ideal fluid since that is what they are made for if there are any available in the higher viscosities

The viscosity will vary depending on the condition of the shocks. As they wear, the clearances get larger and larger so the viscosity will have to increase to allow function. If hydraulic oils aren't available in the high viscosity ranges then straight mineral aircraft motor oils may be an alternative such as AeroShell 100. Most jack oils are about SAE-20 or ISO-46 so thay may not be thick enough.

12-25-2020, 10:05 AM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Ford Shock Absorber Fluid Sponsored Links (Register now to hide all advertisements) I would caution folks to make sure the shocks are empty of any previous fluid before attempting to change fluids. The old glycerin based and castor oil based fluids are not compatible with mineral oils. I would gravitate toward an hydraulic oil with a viscosity that is near SAE 50 motor oil. SAE-50 motor oil is the same viscosity as SAE-90 gear oil but without the sulfuric acid/phosphoric acid based extreme pressure additives. A person may need a conversiion table for the difference between the ISO viscosity grading system and the SAE system since most hydraulic oils are now graded on the new international system. ISO-150 is very near SAE-40 and ISO-220 is very near SAE-50. Hydraulic oils would be the ideal fluid since that is what they are made for if there are any available in the higher viscosities The viscosity will vary depending on the condition of the shocks. As they wear, the clearances get larger and larger so the viscosity will have to increase to allow function. If hydraulic oils aren't available in the high viscosity ranges then straight mineral aircraft motor oils may be an alternative such as AeroShell 100. Most jack oils are about SAE-20 or ISO-46 so thay may not be thick enough. Last edited by rotorwrench; 12-25-2020 at 10:40 AM.