PDA

View Full Version : motor oil vs. hydraulic fluid


burnandreturn
01-02-2004, 12:30 AM
Why do lawn mowers use motor oil instead of hydraulic fluid in the hydraulic systems?

lawnman_scott
01-02-2004, 12:39 AM
they dont

burnandreturn
01-02-2004, 12:43 AM
All the mowers I have use a synthetic motor oil. Mobil One to be exact.

Barkleymut
01-02-2004, 12:49 AM
I don't know why. But I have 3 mowers with hydros and only one has ever had the slightest problem. That was fixed under warranty and I havent had a problem since. Seems as if the motor oil does the job.

65hoss
01-02-2004, 01:17 AM
Originally posted by lawnman_scott
they dont

Yes they do.

Rick Jones
01-02-2004, 01:27 AM
My Toro 36" hydo requires Mobilfluid 424 hydraulic fluid. The newer-style units use Mobil-1 motor oil though.

65hoss
01-02-2004, 01:46 AM
Many hydro w/b and ztr's require motor oil. Some do use hydro fluid. 20w50 seems to be used a lot. eXmark uses Mobil 1 15w50.

Richard Martin
01-02-2004, 04:55 AM
They use whatever fluid the engineers say is best. The World Class T-5 5 speed tranny in my Mustang uses automatic transmission fluid.

David Haggerty
01-02-2004, 05:46 AM
Manufacturers might have thought finding hydraulic fluid by the quart could be difficult for some customers. So they engineered them to operate on motor oil.

I understand there is enough difference they're not interchangeable and that you can't mix them.

I had a 400 series Hustler with a 72" deck that took 10w30 motor oil. My Howard Price HP 180 with a 15' cut used Type F transmission fluid. Now my Toro 580-D takes hydraulic fluid.
I'd considered using synthetic in it, but it takes 40 gallons of fluid.
I still have a couple of gallons of the type F transmission fluid that I have no use for. I've been using it in oil cans for hinges and stuff. Guess I have a "lifetime" supply.

Dave

mosynthetics
01-02-2004, 08:36 PM
Dave,
For a moment I thought I would easily recommend the advantage of AMSOIL's Synthetic Tractor Hydraulic/Transmission Fluid or their Synthetic Anti-War Hydraulic Oil. Both have service intervals of 2-3 times normal oils. However, in checking the prices for a 55 gallon drum I realize the "leap of faith" it would take to consider this.

You might check out these sites for more information.

http://www.amsoil.com/products/ath.html
http://www.amsoil.com/products/aw.html

Barry Crudup

TURF DOCTOR
01-02-2004, 10:20 PM
grasshopper uses mobil 1

lee b
01-02-2004, 10:43 PM
My z uses 20w50 motor oil. Has anybody replaced regular motor oil with snythetic oil in their mowers hydro system? I'm thinking about doing this and was wondering if it would make a difference. My mower has 1000 hours on it, would it help anything or hurt?

ProMo
01-02-2004, 10:50 PM
A cuustomer gave me an old murcury 7hp boat motor and it says to mix 10w40 with the gas.

burnandreturn
01-02-2004, 11:29 PM
I have sent Hydro-gear an email to ask the reason for motor oil instead of hydraulic fluid. When they answer me I will post the result. I believe the answer will lie in the coating abilty of motor oil vs. hydraulic fluid. The oil acts as a lubricant and cooling agent not just a means of transfering force, such as a hydraulic ram.

Most lawn mower systems use a variable displacement piston hydraulic pump, when the steering levers are in the neutral positon the pump is not outputting. In a constant displacement pump there is a bypass system which would be very ineffiencient on a lawn mower.

David Haggerty
01-03-2004, 05:31 AM
Originally posted by lee blount
My z uses 20w50 motor oil. Has anybody replaced regular motor oil with snythetic oil in their mowers hydro system? I'm thinking about doing this and was wondering if it would make a difference. My mower has 1000 hours on it, would it help anything or hurt?

It's never too late to change over to synthetics. Unless it's already worn out.
Synthetics pretty much stop wear at whatever stage you start using it. If the equipment is too far gone the synthetics kind of accent the existing wear. So if your pumps and motors have a lot of internal wear and are starting to let oil bypass, with the synthetics you'll get more bypass. If they're too worn out they'll not perform as well as they did on regular oil. If that's the case just switch back.

But I'd try it at 1000 hrs. I have two Toro 325-D's. When I changed them to synthetic motor oil for their hydraulic systems, one had about 1500 hrs, and the other had over 3000 hours. They're doing fine with the synthetic oil.

Dave