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motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 2:07 am
by gwatts
I've searched and not found an answer about using 303 Universal hydraulic fluid in the DB tractor transmissions. In the US we commonly use some version of 303 hyd fluid. I found in my 990 that the clutch was slow to disengage when I used it. After re-reading my manuals I realized that they were calling for motor oil. I drained the transmission and refilled it with 30 weight engine oil. The clutch now releases as it should.
Has this been an issue for others?
Is the 303 universal fluid an acceptable transmission oil for the David Brown tractors?
Is 30WT engine motor oil really what they designed the transmission and hydraulic system to work on?

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 6:16 am
by PoppyShan885
While doing some research this evening, I came across the following article. It's lengthy, but none-the-less, a good read.

https://www.tractorlife.com/2018/06/19/ ... ic-fluids/

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 10:27 am
by GeoffDEAL
My opinion on oils that DB specified for many models were not capeable of handling the gear loading of hard use in tractor work resulting in hardening worn through on gears and worn out gearboxes that i have experienced on several tractors. The early Cropmasters 30- 25 series were specified SAE 90 which was a proper gear oil and suited to their hydraulic pumps ect. Later tractors with engine oil specification was wrong and in the end resulted in early gear failure the gearboxes on 1200s got so hot you could burn your leg with short boots, i changed to EP80 with extra antie friction additive after original gearbox failed. My original 990 Implematic also had a bad very noisy gearbox due to wrong oil as with the 1200 but got traded on the 1200. The later tractors with power shift had to have a lighter transmission mp oil type oil but still suffered from transmissions getting to hot that one could not hold your hand on trans casting for long, i changed to a synthetic oil and trans was very slightly warm indicating friction was a very real problem. However for the lighter use most DBs get today it is probably not quite so important but a gear type oil will protect your gear box better or one of the specific transmission type oils.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 1:33 pm
by gwatts
Thanks guys you both make really good points. Great article on 303 fluids! I drained the 990 last evening to replace the filter and fluid with the intent to use 30 wt motor oil. I think instead I will use 90 wt gear oil and see how it performs. The transmission case got very hot using the 303 oil and was still quite warm using the motor oil. My tractors may sit for months without use but when I do get on them I'm not bashful about putting them in a bind. My main concern was whether or not the Hydraulic system would function correctly with this heavier oil.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 2:02 pm
by ollek
You may have some problems with the hydraulic system when the SAE 90 gear box oil is cold. This is if your tractor is a Selectamatic, as this hydraulic system does not allays work as it should if a SAE 90, GL-4 gear box oil is used. The best oil for a Selectamatic tractor is today a mineral oil based UTTO (Universal Tractor Transmission oil), SAE 15W-30, Gl-4. This oil type was not available when the Selectamatic tractors were introduced and this is the reason why the recommendation was SAE 30 engine oil. Please note that a Implematic tractor uses a mineral oil based SAE 80W-90, GL-4 gear box oil.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 2:27 pm
by gwatts
Thanks Ollek, I was hoping you would jump in. I've noticed the hot gearbox as GeoffDEAL referenced so I was concerned that the 303 Hyd oil wasn't enough. Since I'm already changing the oil today I was wanting to get the best oil for the application. I was afraid the 80/90 wt gear oil may not work well with the hydraulic system. I gather it will work but may have issues when cold. My tractor is a selectamatic.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 2:41 pm
by db2d
You could also use 15-40 STOU in your Selectamatic transmission/hydraulics if it is available in your country.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sat Dec 01, 2018 3:29 pm
by ollek
About hot transmission. The engine temperature is from 70 to 90 degrees C when the engine is under load and this is not a problems for the oil to cope with this temperature but you will not want to touch the engine, it is very hot for your hand. It is normal for the working temperature to be nearly the same for the transmission when you work hard, but there is no problems with the oil loosing lubrication properties in that temperature. A engine or a transmission oil temperature can be more than 120 to 140 degrees C before the oil becomes too hot. Please bear in mind that a frequent use of the hydraulic system under high pressure will result in higher transmission temperature than only driving would do. Ploughing in depth control or heavy loader use are examples of frequent use of the hydraulic system.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Sun Dec 02, 2018 1:12 pm
by ollek
It is very misleading to call a oil "hydraulic oil", if it is used in the transmission. Any transmission running on hydraulic oil will fail. A engine or a transmission oil can be used as a hydraulic oil but a hydraulic oil must never be used in the engine or the transmission. The oil called UTTO is a transmission oil that is formulated to be used in the hydraulic system as well. U=Universal, T=Transmission, T=Tractor, O=Oil. A prefix S, means that the oil can be used in wet disc brakes as well. This oil is called SUTTO. The STOU mentioned by db2d is the European equivalent to SUTTO.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Mon Dec 03, 2018 11:04 pm
by gwatts
I guess you're right Ollek. The more precise we are with our terminology the better our communications will be.
Thanks for all the help.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Tue Dec 04, 2018 8:05 am
by philedge
ollek wrote:
Sun Dec 02, 2018 1:12 pm
The STOU mentioned by db2d is the European equivalent to SUTTO.
Are you sure? As I understand it SUTO(STOU if your French) is for engines and transmission. UTTO is for transmissions only, hence the extra T. If the S in SUTTO is an improved version for use with wet disc brakes then that doesnt make SUTTO the same as SUTO/STOU!
Maybe the terminology over the pond is different?

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Tue Dec 04, 2018 8:12 am
by ollek
Yes, I am sure, if we are talking about a oil for transmissions and hydraulics, as is the case in this topic. STOU is not French, it is short for Super Tractor Oil Universal, 4 very English words, and used all over the globe, also in France, UK, US, and so on. This oil is good for transmissions, hydraulics and engines. UTTO is short for Universal Tractor Transmission Oil, 4 very English words, and used all over the globe. This oil is good for transmissions and hydraulics, but NOT for engines. There is no oil called UTO or SUTO, but you sometimes see this abbreviation used, even it is wrong. STOU is mostly used in Europe and SUTTO in the US. The Americans use a separate engine oil, as they normally do not believe in a multi use oil. STOU is very difficult to get in the US, so they use SUTTO. And yes, the letter S stands for a oil that can be used in wet disc brake applications. All abbreviations mentioned are international and used in all countries and in all languages. Please note that one of the first oil companies to make a STOU oil was British Petroleum. This happened in the 1970s and the oil was later upgraded to a STOU specification.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Tue Dec 04, 2018 12:59 pm
by philedge
Ok. So SUTTO can be used as engine oil?

BTW whilst STOU is an acronym of English words, the order of the words is the French way according to at least one oil supplier. SUTO is the english language version:)

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Tue Dec 04, 2018 2:15 pm
by ollek
NO, SUTTO can NOT be used as a engine oil, it is a oil for transmissions, hydraulics and wet brakes ONLY. UTTO and UTO is the same oil with no additives to suit wet disc brakes. Please read my comments correctly. The prefix letter "S" tells that the oil is good for wet disc brakes and this has nothing to do with the engine. I have said all this several times, but it sounds like you have problems in understanding what I am saying. The oil supplier you refer to is wrong, STOU is an international marking, that is used all over the world, also in France. SUTO and/or SUTTO and UTTO or UTO if you like, are transmission (hydraulic) oils that are NOT suitable for engines. STOU (TOU) is suitable for transmissions, hydraulics AND engines.

Re: motor oil vs 303 Hydraulic Fluid in trans

Posted: Tue Dec 04, 2018 3:53 pm
by philedge
Ive read your comments correctly and am indeed struggling to understand what you are saying. 6 posts back you said STOU is the European equivalent of SUTTO and now youre saying they are different!

You might want to google SUTO oil, as theres alot of suppliers saying its not only a transmission oil, but suitable for engines aswell.