by Sam Dillinger (comments: 0)

When Should I Change My Transmission Fluid

Transmission Fluid Change

This is a question that is near and dear to my heart, and it’s a question I hear all the time. This topic is near and dear to me because I've spent the bulk of my career repairing transmissions of every kind. I see so many transmission failures that could've been prevented by regular servicing of the transmission, and these failures end up costing people a lot of money. Several years ago a transmission service was regularly recommended maintenance at any shop you'd visit. The advent of new, longer life, transmission fluid has cut down on this dramatically, but the majority of cars still on the road, are using fluid that needs to be serviced regularly. No one is talking about it anymore! So let’s take a little closer look at it, and see how this can effect you.

First, let’s start with recommended maintenance schedules. I’ve never had much faith in the schedule that’s printed in the owner’s manual of all vehicles. We’ll look at a general idea of the recommended maintenance schedule for the transmission only in this article, and save the other fluids for a different day. When I got into the business the generally accepted idea was to service the transmission every 30,000 miles. Normally if you stuck with this schedule, you would get a good, long life out of your transmission, barring any kind of defective parts. Around 10 years ago the schedule switched to 60,000 miles. This coming even though most vehicles were still using the same transmission as the previous model year transmission. There are additives and detergents that are more advanced, and offer better protection, but it’s still a petroleum based fluid and is subject to heat and wear, like any other fluid. I have my suspicions about this, but that’s all they are: suspicions. So instead of un-founded theories, I’ll offer you my professional advice, as someone who sees broken transmissions all the time, and is intimately familiar with why they fail.

My advice is simple, and probably pretty predictable at this point of the article, service your transmission regularly! It’s that easy. The average car owner uses their vehicle more now than ever before, and with that increase in usage, it needs to be rigorously maintained. There are still times that a transmission will fail at low miles due to a defective part. That being said, the majority of transmission failures I see are due to a deteriorated torque converter clutch, that could've been prevented by regular maintenance. By renewing the fluid, you’re renewing the additives and detergents that are made specifically to protect your transmission. For organic fluid (just regular petroleum based fluid) I recommend every 30,000 to 35,000 miles. For vehicles with full synthetic, or a blend of synthetic and organic, I recommend every 55,000 to 60,000 miles. If your vehicle is one that has a filter that is replaceable, then do so. Don’t flush the fluid with a transmission fluid flush machine (I don’t recommend a transmission fluid flush machine ever) but instead have the pan removed, the filter replaced, and the fluid replaced. Just like an oil change, you wouldn't do it without replacing the filter. The only exception to this would be for the vehicles that have to have the transmission disassembled to replace the filter. For these units, just draining out the old fluid and replacing with the factory recommended new fluid is perfectly acceptable.

The trend in the industry is to only recommend a transmission fluid change when the fluid is dirty. The whole point of preventative maintenance is not to ever let it get that far. If your vehicle has 90,000 miles and has never had a transmission service, don’t go and get one now. Transmission is essentially a high detergent cleaner, and it will cause more harm than good to replace really dirty (dark brown, burnt, or blackened) fluid at this stage. The only advice I can offer in that instance is not something anyone wants to hear- start saving your money for a major transmission repair. That will be the next step unfortunately. I have seen way too many failed transmissions that just had the first service 2 weeks ago, and the vehicle has 95,000 miles. So, in short and to avoid that costly fate, service the fluid when it’s still clean and working correctly!

A quick note about manual transmissions: the internals of a manual transmission vs an automatic are completely different. The service interval is different as a result. For organic fluid, every 45,000 miles, and for synthetic fluid, 70,000 miles is fine. By following these guidelines you’ll give your transmission the very best chance at a long and happy life with you!

As always for my members, feel free to send me an email from for advice, questions, and concerns.

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Meet Sam Dillinger

My name is Sam Dillinger. I've been a professional, dealership technician for 18 and a half years. My first introduction to mechanical repair was when my own vehicle broke down in the fall of 1995. I was 18 and couldn't afford to pay to have it fixed. So I borrowed tools and asked a ton of questions and, eventually, was able to replace the clutch on my truck by myself. During the course of that project, I found that I really enjoyed having a wrench in my hand and figuring out the puzzle of disassembly and reassembly of a motor vehicle.

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