The Maxima 5w is close to the KYB viscosity.

I saw some posts on TT that said lighter viscosity oils like 2.5w reduces dampening which is a common tuning tool, but it can create other issues when the light oil gets hot and further reduces viscosity.

You can put different oil in both chambers, but over time the inner and outer chamber oils mix and blend together.

Good stuff, I can use up the old 5wt i have in tbe shed on the fork outers at the next oli change;)

Motorex 2.5w has the same ratings as the kyb oil and is good stuff.

Anyone every try any other types of oil like ATF or hydraulic fluid?

you would be doing a lot of trial and error if you do not know their viscosity. So many other variables with suspension rather just stick with one oil

The options are ATF or hydraulic fluid.

Not sure on the viscosity of various ATF brands but hydraulic fluid is fairly simple as the ISO standards equate to specific oil weights. For example the ISO 22 oil is equivalent to 5w oil.

Hydraulic fluid is WAY less expensive than fork oil. Like WAY less expensive.

Hydraulic fluid is less expensive. But if you try finding correct synthetic hydraulic fluid, things get much more expensive and are usually sold in bulk.
If mineral is fine, then no problem.

just going off the sales pitch of suspension oils, does the ATF have the non foaming properties of suspension oil? and also longevity (and consistency iro not fading) of being forced through valves multiple times per second

I don't know the answers, but just two questions i would be trying to find answers for

I am going to try some of the Amsoil 5w light Shock Therapy suspension oil.

I was an engineer with GM's Hydra-matic (aka, High-dramatic) automatic transmission division in the 1980s. I spend alot of time with ATF.

1. Yes, ATF has anti-foaming agents. Foam entrains air in ATF, which reduces its bulk modulus (stiffness), which affects clutch timing (rate of engagement/disengagement) as the fluid "pushes" against a spring. Automatic transmissions have significant spinning elements, all of which work to "whip" the oil. Foam also causes pump cavitation, which causes excessive wear on the pump as well as adversely affects shift quality. Foamy oil is very detrimental to performance, so anti-foam elements are added to everyone's formulation.

2. ATF also has to deal with the pump, pressure regulator/relief valve, and the valves which operate in the valve body. All of those operate at relatively high frequency (pumps at much higher frequencies) than oil passing through a shim stack, so a suspension application won't pose a problem for forks/shocks.

ATF also contains solvents/detergents which keep the hydraulic valves in the transmission clean, free from sticking, and generally happy. That will work to keep your shim stack clean.