Should you change transmission fluid and how often?

Great insight as usual! Coincidentally I was thinking about taking my car for transmission fluid maintenance... I bought it used recently without much maintenance history, so I think it would be good to do it just to be on the safe side

I've always changed the transmission fluid in my Fords at 100k miles. Never had any adverse effects. Never had a bad Ford transmission. I've always left the lifetime fuild alone in my Hyundais, and they have always lasted ~300k miles before I sold them.

Thanks!

If You like to keep your vehicles for a long time, keep the trans oil changed at no more than 30K , or take a chance at a new trans at about 100K if your lucky. Fluid changes are much cheaper in the long run. Just common sense to me. Lifetime oil usually means it will last until the warranty expires. The CVT’s are even worse.

If a partial transmission fluid change changes 50% of the fluid, then three changes will change more than 90% of the original volume (that's just mathematics). Just drive 50-100 miles between changes to mix the new fluid with the old. If the partial fluid change is any greater than 50%, then three changes will change 99% of the original volume. I've seen many modern cars changed at 90,000 miles without a problem if they weren't already displaying a problem...most modern transmissions are not that delicate. A close examination of a sample of the old fluid for clutch particles will prove it out.

My volvo mantenerse book says that has to be changed every 100.000km

I have changed fluid and filter on 2 cars in my life and the had NO prior problems. After the change and I used everything from the dealership, BOTH cars developed slipping and or hard shifting with-in a year . Both cars were high mileage. I will NEVER change my fluid again...EVER ! If it ain't broke....DON'T FIX IT !

At 90k miles with no prior service, a drain and fill generally would be ok

I will sell you a hamburger, a meal, and I will say it is a lifetime meal. You will never have to eat again the rest of your life. I will be correct no matter how long you live.