Friday, February 3, 2023


When should you service your transmission?

Courtesy Motorhomes of Texas

Silverxxx on wikimedia commons

If you are undecided about whether or not you should service your transmission or when to service it consider this: Transmission failure is most often due to fluid failure. Mechanical parts failure is in the minority when blame is laid. The breakdown and failure of transmission fluid is precipitated by two elements: contaminants and heat — with heat winning the race for worst/biggest contributor.

Transmission temperatures run generally in the same range as engine temperature until put under a strain. Heat in the transmission will usually climb higher and faster than engine temperature, with normal “tranny” temp being in the 175 F to 200 F range, and hill climbing takes it up from there.

At 175 F, fluid will last about 120,000 to 140,000 miles (discounting the contamination factor). Its life expectancy decreases almost exponentially with increased heat! At 200 F the breakdown occurs at around 60,000 to 70,000 miles. As you can see, an increase of only 25 degrees can cut the life almost in half. Below is the increase versus the fluid life:

• 225 degrees = 35,000 miles
• 250 degrees = 20,000 miles
• 275 degrees = 10,000 miles
• 300 degrees = 1,500 miles
• 325 degrees = 500 miles

Short periods of time at higher temperatures also take their toll, but trying to calculate exactly when you should change the fluid has to be done on an individual basis. If you pull a toad and drive in the hills or mountains, you need to service more often. Most high-end motorhomes have transmission coolers and many have temperature gauges. If you don’t have these two items, it might be beneficial to have them installed.

Ideally, servicing your transmission would be done as often as every other oil change, but that’s just not practical. It would be plenty expensive, and at some point it ceases to be cost-effective. The point is: Be aware of the health of your transmission fluid. Monitor its operating temperatures and service accordingly. Servicing too often won’t hurt your wallet nearly as bad as overhauling the beast.



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