Is this mechanic right?

My wife and I have Ford Explorer’s - 2010 and 2009 w/59K and 65K miles. A couple of months ago, on my wife’s Explorer, I had the two rear axle seals replaced that go into the rear differential because one was leaking and the other one looked like it was about to go. A week or so later, the pinion seal going into the differential started to leak and I had that replaced. This was done by a mechanic who I trust and have used a few times before but is located in another state ~ 2 hours away (I was on vacation and decided to have these done). Everything has been fine since and it drives fine. I now noticed that my 2009 Explorer has the same issue with the inner rear axle seal on the driver’s side and I’ve made an appointment to take it in next week to a local mechanic (close to my house) who was recommended to me. He “specializes” in drive trains/axles, etc… When I called he started to explain that rear seals don’t just “go” but that something is causing them to fail. He mentioned that it could be that the bearings in the differential are “tired” or there may be metal shavings in the fluid or even that the wheel bearing (rear) are gone. In short, he said that he replaces a lot of Ford Explorer rear inner axle seals and that it’s never just the seal but something else which causes the seal to fail. Should I find another mechanic or is this one telling the truth ? And if he is telling the truth, should I expect my wife’s Explorer, that had the seals replaced a couple months ago, to fail again (because of an underlying condition) ?

Sounds legit to me. Also seems like 59 and 65K are low miles to be fixing rear-ends - unless there’s something particular about those I’m not aware of.

He’s right, though. Keep an eye on your wife’s and see if it starts to leak.

You can also try, with the parking brake on and vehicle in neutral, sliding under the truck, and try moving the rear input by hand. It should be rock solid. If you feel any play, then there’s something else wrong, and if you just repair the seal, it’ll go again in short order.

Be careful, we don’t want the truck rolling over you. Once you lock it in place, try moving it first, before you get under it.

A Google search for “what causes ford explorer axle seal leak” didn’t find any mention of why the seals fail.
A second opinion is a good idea.

Whenever replacing the axle seals, I always replace the bearings too. It is little added to the bill and you already have it that far apart already. I just did my Dakota’s because of a leaky seal and the bearings were only an extra thirty dollars and an extra 20 minutes to do.

Granted this is pretty low miles for either vehicle to have an axle seal go bad, but it happens.
You can confirm that the seal is leaking if you see the inside wall of the rear tires is wet with oil residue.

As far as the pinion seal leaking so soon after the axle seals were replaced, there is no way that the 1st mechanic could have predicted that and he would not have caused the pinion to leak.

There is no way to look at a seal and predict that it is about to fail. The axles would have to be pulled to even see the seal.