Scag SWZ hydro Fluid

[onelegjohn]

I just bought a used scag 52" SWZ - I need to know what kind of Hydro fluid to put in the reserve. I went to Tractor Supply and bought universal hydraulic fluid (tractor transmission) 10W-20. They had Hydraulic Oil, but I didn't know what to get. I don't want to damage my pumps by getting too thin or too thick viscosity oil. The "Oil" was 20 weight. I am a chemist and this is a mystery to me....Can some one point me in the right direction.

Thanks,
Nate

[LawnSmith]

the SWZ is a walk behind right? if so, my 1998 scag hydro walk behind uses 10w30 motor oil. but my TT's use the 20-50.

[onelegjohn]

Can you check your manual to see the specs on the hydro trans requirements...as I don't have a manual. I have ordered one but I need to know before I add the oil. Thanks for the response.

Nate

[onelegjohn]

I am assuming the early 90's WB's used 10w-30 in their hydro trannies then. I am pretty sure I will be safe with the 10w-30 -



- Does anyone know if hydraulic oil is ok to use? -

[SJR Lawncare]

I have a 2001 Scag swz52 & the manual calls for 4 qts. of
SAE 20W50.

Good luck, Steve

[Mark]

I have a 2002 SWZU 52' hydro, Steve is correct SAE 20-50 for your Hydro mine also takes 4qts,,,,, Marks Mowing Service

[gaunlet13]

Mobil 1 15w50 is what I put in my 2000 mdl STT.
Talked w/Scag about it and they said it is an over kill but ok.
I figured less friction gives less heat (good thing). I'm hoping that it will help the pumps last longer.

[lawnkid]

I use fully synthetic Mobil 1 20W50 for my 1996 52" SWZ and it works great but it is kinda expensive cause it's a racing oil. Oh well,
Peace

[Jimbo]

My Scag 52" Tiger Cub calls for 20W-50 for the Hydro oil, and straight 30W or 40W for the Engine oil depending on Temperature. I use 40W since I dont mow below 40F.

This info is straight form the manual!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Good Luck
Jim

P.S. Buy the manual it's cheap.

[onelegjohn]

FYI - The oil has two numbers the first being the viscosity or thickness when warm - the second is the thickness when cold. So - really you could be making your pumps work harder using 20 weight intead of 10weight. The 20 is thicker and harder to push.

Nate

[Jimbo]

The oil has two numbers the first being the viscosity or thickness when warm - the second is the thickness when cold. So - really you could be making your pumps work harder using 20 weight intead of 10weight. The 20 is thicker and harder to push.


The quote above provides incorrect information.

Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature.
Exp: 10W30 (10W when cold, and 30W when hot)

If your manual calls for 20 Weight use it. It doesn't matter if it is harder for the pump to push the fluid. The pump was designed to use 20W due to tolerances of the internal components.

People shouldn't give advice that could harm someones equipment if they dont know what they are talking about!!!:angry:

[Jimbo]

Oops Im sorry about that Onelegjohn. I didn't notice that you started the thread.

Your allowed to damage your own equipment.

Good Luck!

[onelegjohn]

I don't understand - I have an older Scag and 1993 manuals call for 10W-30 in the pumps. I could have sworn when the oil heats up it gets thinner...maybe I am wrong. Should I use the 10W-20 Hydro Oil then? I am also curious - as to what to use in the engine then. Straight 30W is what I use but it seems that 40W would be better suited for hot weather. I swear when it heats up it comes out REAL thin. Jimbo - can you clarify?

Thanks,
Nate

[Jimbo]

Hello Nate,

I read your other post and I think you are thinking too much. You need to use the oil which your manual states. There could have and probably have been internal engine tolerance changes over the years which then change the oil requirements. Scag gets the requirements from the pump and motor MFG's and lists them in their manuals. My new Scag came with a seperate motor manual from Kawasaki.

To an extent you are right "Oil will get thin when hot", that is why the manuals call for solid 30 (or straight 30W) from like 30-90 degrees, and Straight 40W for say 45-100+ degree (These Temp's are not exact, but close).
However where you are confused is that multi-weight oils work differently. These oils have special additives which allow the oil to be thin upon start-up, and then as the engine heats they become thicker.....To a point. If you go beyond the heat threshold these oils will also start to thin out. Thats why it is important to match the second number to the expected temperature that you will be working in. Exp:5W-40

The main reason for the existance of these multi-weight oils is due to pressure from car manufactures. For instance most new cars state to use 5W-30. This is not great for the engine longevity, but it can be achieved due to tighter machining tolerances, and it makes for good gas milage numbers to make the EPA happy.

I know this was a long one but I hope you come away with a better understanding.

Jimbo

[onelegjohn]

That helps a lot. I actually did a study in one of my chem classes on different brands of the same weight - to see which oil lasted the longest. I should clarify - which additive different companies used that would last longer. Before additives is was 1000 miles and time to change the oil. Now the additives give 3000+ miles to a automobile. Oxidation is the key to longevity - if the additives (which all oxidize eventually or the engine wouldn't work)oxidize they lose their physical quality we use them for. Then the oil becomes basically useless like the old oil used to. I am not a gearhead but I like to mow grass - I do the best a chemist can! I'll tell my strength is definitely lawn chemicals - I hope to have my own company soon - Lesco - here I come!!!

[Doc Pete]

Originally posted by Jimbo



People shouldn't give advice that could harm someones equipment if they dont know what they are talking about!!!:angry:

FWIW,
I've been on the phone all day about pumps and wheel motors. The company "Hydro Gear" which supplies pumps for many machines suggests 20w50. Also, the heavier weight oil helps reduce the effects of pump blowby as the pump starts to wear. Also, they said whatever weight the pump can handle, will also be easily handled by the wheel motor. I can say that switching from 10w30 to 20w50 is noticable. The response is better and more precise.
Pete

[Jimbo]

?????????What did my quote have to do with your response switchless?

All I said was to use the factory recommended oil weight (and I explained how the multi-weight oils work.

[Doc Pete]

Originally posted by Jimbo
?????????What did my quote have to do with your response switchless?

All I said was to use the factory recommended oil weight (and I explained how the multi-weight oils work.

Well Jimbo, "All I said" was to repeat honest correct information from a reliable pump maker, which may answer questions people may ask about the difference between 10/30 and 20/50 oil. And, I thought "reliable information" from people "who know what they are talking about" is pretty much exactly what you quote stated. That's all.
Pete

[Shultz]

I think on www.scag.com you will find a link to download the manual as long as you have the serial number.

[Jimbo]

Switchless, I still don't know what you are talking about, so I will just drop it. I re-read the posts and I guess what you are saying is that you agreed with what I said and re-posted it?? Is that what you are saying?

Or are you saying I gave incorrect info?

[Doc Pete]

Originally posted by Jimbo
Switchless, I still don't know what you are talking about, so I will just drop it. I re-read the posts and I guess what you are saying is that you agreed with what I said and re-posted it?? Is that what you are saying?

Or are you saying I gave incorrect info?

Yes Jimbo, I'm totally agreeing with you. The info I added was "as you suggest" from "someone" (the pump company) of which is a "reliable and knowledgable" source.
Thanks,
Pete

FWIW, I ran my machine again today and the 20/50 definitely is more accurate than the 10/30.

[cnflawn]

hi guys,
this is an easy one.
scag swz used 10/30 untill 98 models then went to 20/50.
the way to tell is if the hydro tank is plastic it takes 20/50 if its metal use 10/30.
also use only a scag hydro filter.
DO NOT USE hydo fluid.
the RIGHT engine oil will changer per manufactuer of the engine.
jerald

[Jimbo]

Thanks for the clarification Pete.

Jerald-

What was the change back in 98' which caused the oil weight change? New wheel Hydro Wheel motors, which were a different design, and different ManufacturerI bet.

If I am right this should help prove what I have been saying about always going with recommmendation in the manual.

Thanks
Jim:blush:

[cnflawn]

hello jim,
you are exactly right on two issues. first it was a motor change and cooling tank change not a pump change. the swz still has the same hydro-gear pump since its inception. second and most importantly always follow the manufactuers recommendation. they have looked at the whole unit its weight and cooling ability and pressure requirements so go with what they say. also in this case where vendors like hydro-gear and sunstrand are used by a manufactuer they too test the unit and approve the application with a certain type of fluid before they will extend a warranty to the manufactuer.
sorry so long but this is a big issue. just because it has the same pump or motor does not mean it uses the same fluid.

jerald

[Doc Pete]

Originally posted by Jimbo
Thanks for the clarification Pete.

Jerald-

What was the change back in 98' which caused the oil weight change? New wheel Hydro Wheel motors, which were a different design, and different ManufacturerI bet.

If I am right this should help prove what I have been saying about always going with recommmendation in the manual.

Thanks
Jim:blush:

Jim,
Funny, but in talking with the pump company and then the mower maker, it's possible that oil recommendations we done more for convinience. In other words, for a while 20/50 was not easy to find at the local store and 10/40 was. In fact, the mower maker of my machine just mentioned that they will be recommending 5/30 for their machines, which is the current oil most newer cars use and easy to obtain.
However, I can also see from my experience with 10/40 and 20/50, the "lighter" oil is more forgiving and "softer" so it will make the mowers less "touchy" to use.
Pete

[Purcell McCue]

Go to Scag.com and download your manual, just need the model and serial no.