What type of hydraulic oil do you use in a exmark Lazer z zero turn lawnmower?

eXmark Lazer Caster Wheel Bearings Zero Turn

I can help you, but I don't know what you're asking. I have an extensive knowledge of Exmark mowers.

drain and replace your hydraulic steering system oil and replace the hydraulic filter then refill system

JD Mower Maintenance - YouTube

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https://www.youtube.com/watch?v=RYeP_QLhsoU
Mar 31, 2013 - Uploaded by GreenMachine757
Doing routine maintenance on my John Deere 757 zero turnmower. ... DIY Mower Seat Repair - Garden Tractor Seat - Zero Turn - eXmark ...

John Deere Tractors Information - SSB Tractor Forum

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Service Transmission - John Deere Ag - New Equipmentmanuals.deere.com/cceomview/OMM144042.../OMM144042_D010.ht...DO NOT mix oils. These tractors are equipped with a hydraulic wet disc PTO clutch.... DO NOT use type "F" automatic transmission fluid. John Deere Low ...JD 445 Rider Mower Issues - Need Help Please - GardenWebforums2.gardenweb.com > Garden Forums > TractorsNov 12, 2009 - But I've read a lot of threads hoping to read about my issues, and was ...What tools I don't have my friends do, and both are real mechanics, big Deere fans ....it steer hard due to lack of fluid in the hydraulic steering cylinder. ... You may need to add fluid, run the tractor around a bit, and then check it again.

Try adjusting belt tensioner.

That's going to be expensive. You will need to take it to a shop unless you have a lot of specialty tools. Example : hydraulic flow tester and a very good understanding of hydraulics

you mean it dies or the engine slows down ???

My problem is that I don't know what your problem is exactly.

it might take a couple oil changes clear it all out of the engine just run it without a load on it till its flushed out

I don't understand why you want to change, it is a closed system, so no contamination can get in. Anyway, there should be a small tank somewhere where the hydraulic oil is checked. You can siphon the oil out of there with a oil suction gun or turkey baster, and replace it with new fresh oil.
Do you have a reason why you think the oil is contaminated or has been overheated? It is quite a rugged oil meant to stand up to brutal environmental conditions like continuous use in high heat, and in plow trucks operating in extreme cold with continuous duty.