Is Synthetic Transmission Oil Worth The Cost?

Mechanics Hub - February 8, 2014
Fleet Preventive Maintenance Notes – Synthetic Transmission Oil

It was several years ago when a salesman from the Detroit Diesel dealership came in and was promoting the benefits of synthetic transmission oil. Their parts department was selling it of course and the price was astronomical in my mind. We were paying around two bucks a litre for Dexron oil while the synthetic was four or five times that price.

Sold On Synthetic Oil

It took a while to warm up to the cost but talking from experience the cost is well worth it. The maintenance is cut down drastically since synthetic transmission oil does not break down increasing time and mileage between services. Transmission services in our fleet aren't required for 2 to 3 years depending on mileage.

Mechanical Failures Are Non Existent

It's been years since there have been any mechanical failures on our Allison transmissions. It's amazing how they keep on going without any problems. The 2000 series models in our fleet come with Prognostics. It monitors oil and filter life along with a health check system that monitors wear on clutches.
How To Tell If You Have Prognostics On Your Vehicle

This is an easy way to tell if your vehicle is prognostics enabled. Watch for the OEM installed service indicator light. It lights up for 5 seconds during start up on vehicles with Prognostics. The first 5 seconds is a bulb check then the indicator light will come on for 3 seconds to indicate that prognostics is enabled and ready to go.

When one of the monitoring parameters are reached the “trans service” light is illuminated to tell the operator that maintenance on the transmission is required. If action is not taken and the “trans service” light is not reset then the “check trans” light will come on along with the “trans service” light.

By the way to use this system the transmission oil must be Allison approved TES 295 and TES 389 oils. Using any other oil will create problems and possible damage to the transmission. Approved oil can withstand longer intervals between services compared to sub-grade oils. This system works great if you follow the guidelines.

The Importance Of Proper Fluid Level

Everybody knows the importance of a proper transmission fluid level but a lot of people don't know how low and high oil levels effect the transmission. If the oil level is too low the torque converter and clutches will not have enough oil to operate properly and overheat. If the oil level is too high the oil will develop aeration causing poor shifting and overheating.

It was 2008 I believe the last time we replaced clutches in a transmission. The 3000 model Allison was climbing a long grade every day and the clutches had worn down. At that time we were using regular Dexron III and then on to Dexron IV. Since then I'm convinced using synthetic oil has been a big reason why repairs have been reduced to nothing.

The cost of synthetic transmission oil is shocking at first but believe me the extended life you will get from your automatic transmission will make the original oil investment well worth it. I support the use of synthetic oil in drive trains because of the low maintenance and longevity it adds to components.

If you agree or disagree with using synthetic oil please add a comment below.