Does the Right Oil Matter?

Charlie Admin • 4 February 2026

Does the Right Oil Matter?


Short answer: yes. Very much so.


Recently, we had a John Deere 5720 come into the workshop with a complaint of noisy and ineffective brakes. At first glance, it sounded like a fairly routine brake issue, but as soon as we removed the trumpet housing, the cause became clear almost instantly.


Let’s just say… it didn’t take Sherlock Holmes long to crack this one.


What We Found


On strip-down, we discovered that the friction lining on one of the brake discs had completely separated from the disc itself. With the lining gone, the metal backing plate had been running directly against the brake piston.


The result?

  • Severe scoring to the brake piston
  • Extensive internal damage
  • A braking system that was never going to perform as it should


While we were in there, we also removed the handbrake discs for inspection, and it’s a good job we did. They were well past their best and heading in the same direction.


At this point, the obvious question was why. So, What Caused It?


We can’t say with absolute certainty what caused the failure, but based on what we saw and our experience, we have a very strong suspicion. The wrong oil.


And that got me thinking. 'This would make a good blog case study'. So, here we go…
"Does the right oil really matter?"


Why Oil Choice Is Critical in Modern Tractors


On older machines, oil choice was often a little more forgiving. Today’s tractors are a different story altogether.


Modern tractors like the John Deere 5720 rely on one oil to do multiple jobs, including:


  • Lubricating the transmission
  • Operating the hydraulic system
  • Cooling and protecting internal components
  • Providing correct friction characteristics for wet brakes and clutches


That last point is the key one here.


Wet brake systems are designed to work with oils that contain specific friction modifiers. If the wrong oil is used, even if it’s a “good quality” oil, those friction properties can be completely wrong for the system.


Over time, this can lead to:

  • Brake chatter or noise
  • Reduced braking performance
  • Overheating
  • Premature wear
  • Brake linings breaking down or delaminating (exactly what we saw here)


“But It’s Still Oil, Isn’t It?”


Unfortunately, not all oils are created equal.


Using an oil that almost meets the specification, or is intended for a different application, can slowly cause damage that isn’t immediately obvious. The tractor may continue to work, but internally, things are deteriorating.


By the time symptoms show up, the damage is often already done.


The Cost of Getting It Wrong


In this case, what could have been avoided with the correct oil has resulted in:

  • Brake disc replacement
  • Brake piston damage
  • Additional labour
  • Increased downtime


All of which could have been prevented.


Our Advice


  • Always use the oil specified by the manufacturer
  • If in doubt, ask, don’t guess
  • Be cautious of mixing oils or topping up with “whatever’s to hand”
  • Regular servicing isn’t just about filters, oil choice matters just as much


If you’re unsure what oil your tractor should be running, or you’re experiencing brake noise, chatter, or hydraulic issues, it’s well worth getting it checked sooner rather than later.


Who We Use For Lubricants


At JJ Farm Services, we choose to use Morris Lubricants, a trusted UK oil manufacturer with a long-standing heritage in producing high-quality lubricants.


Morris have been blending and manufacturing oils in the UK for decades, and their products are designed to meet the demands of modern machinery, including tractors with shared transmission, hydraulic, and wet brake systems.


One thing we particularly value is the oil lookup tool on their website (
www.whatoildoineed.com), which is completely dedicated to helping users find the correct oil for: Cars, Trucks, Buses, Tractors, Agricultural machinery, Plant and construction equipment.


It removes the guesswork and ensures the oil being used is exactly what the machine was designed to run.


I’ve also had the privilege of visiting the Morris Lubricants factory in Shrewsbury, where all of their oils are manufactured. Seeing the operation firsthand really reinforces the confidence we have in the product, it’s an impressive setup and a clear demonstration of the standards they work to.


Final Thoughts


So… does the right oil matter? Absolutely!


As this John Deere 5720 proves, oil isn’t just oil, it’s a critical component in keeping modern tractors reliable, safe, and working as they should.


Using the correct specification oil, from a trusted manufacturer, can prevent costly repairs, reduce downtime, and extend the life of your machine.


If you’d like advice on oil choice, servicing, or if you’re experiencing brake noise, chatter, or hydraulic issues, feel free to get in touch. We’re always happy to help keep machines working and avoid costly repairs where possible.

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