Hydraulic Cylinders

Extent them as far as possible. Wipe the rod clean with a rag,pay special attention to the top of tye cylinder to remove dirt. spray lightly with oil, retract.

Keep assemblies clean. Then as noted in previous post oil lightly.
If you have kick down jackes, make sure that assembly is clean. Mine has a roller bearing that must stay free. I clean it off with brake clean and then lubricate with chain lube or step lubricant.

What is the best oil to use?

Depending on the jack (READ THE FINE MANUAL) Silicon lub or Tranny Fluid (Same as INSIDE the jack) would be my suggestion.

Power gear does not mention it in the owner's manual but on SOME jacks they have a ZERK.. a couple strokes of White LIthium is suggested by folks I respect.

Are you talking about HWH jacks? HWH has some very specific directions on these hydraulic rams. There is other info presented in HWH instructions. Download it and read.

(
FROM:
ISSUE DATE:
HWH CORPORATION
R
Cleaning the jack and jack rod.
In general, HWH jacks require no regular maintenance. Under normal circumstances, lubrication of jack rods is not necessary or advised.
If a jack gets coated with dirt or mud it is advisable to clean
the jack. It is acceptable to clean the jack as a part of normal maintenance but is not required.
of jack rods is not necessary or advised.
Note: The 9000# and 16,000# kick down jacks have a roller bearing above the actuator rod.
This bearing must roll freely for proper operation of the jack. It is a good idea during regular maintenance
that this bearing is checked to make sure it does roll freely. If the bearing is frozen or does not roll freely,
use WD-40 to loosen the bearing and then apply a few drops of motor oil (used is fine) to lubricate the
bearing. See diagrams on reverse side.
BLOCK FRAME AND TIRES SECURELY BEFORE CRAWLING UNDER
VEHICLE. DO NOT USE LEVELING JACKS OR AIR SUSPENSION TO SUPPORT VEHICLE
WHILE UNDER VEHICLE OR CHANGING TIRES. VEHICLE MAY DROP AND/OR MOVE

Basic cleaning of the complete jack assembly is accomplished with the use of soap and water.
Spaying the jacks with a spray wand at a car wash would be acceptable.
The only time a jack rod would need cleaning is if the jack has been extended for a period of time.
The jack should not be extended just to clean the rod.
WARNING:
If the jack is extended, use soap and water or WD-40 on the jack rod then wipe the rod dry with a clean cloth.
Do not use a dirty rag to wipe the jack rod or do not wipe the jack rod if it is coated with dirt.
This could scratch and damage the rod. Make sure to use water or WD-40 to loosen any dirt before
wiping the jack rod.
If the jack rod has been greased or silicone sprays have been used on the jack rod, use WD-40 to loosen
the grease or silicone and wipe the rod clean.

Thanks Pigman1. Very helpful. I do not have HWH jacks, but much of the info still applies.

What brand of jacks do you have?

I think they are level up by lippert. They are on a 2013 Mobile Suites fifth wheel.

I spray mine with a silicon lube.

Clean and wipe down with silicone spray, right from Lippert.