Next we'll learn he doesn't check tire pressure either.

 

At least ford has service intervals. My friends Sierra 1500, not even kidding. The front diff service interval in the manual is "Don't do anything unless its making noise" Well, his started to make noise, and then he drained out paste. He now drives an F150.

 

How many miles, and under what usage? That's actually a common recommendation for light-duty vehicles, and they usually do fine. I don't think any of my vehicles had a specific recommendation for servicing differentials until I started buying 4x4 SUVs and trucks with some expectation of towing and carrying loads. I suspect most new-vehicle buyers never service the diffs.

 

2005 Durango. Service manual has a Schedule A and a Schedule B, both only go to 120k miles. I've always done Schedule B which calls for 15k differential fluid changes and drain/refill trans with filter change every 60k. Funny thing is Schedule A doesn't call for either of those at all. Had a friend whose uncle worked at a Dodge dealership and I remember him telling me they had a stack of rear ends in the shop several years back. Makes you wonder.

From the manual......

Schedule “B”
Follow schedule “B” if you usually operate your vehicle under one or more of the following conditions.
• Day or night temperatures are below 32° F (0° C).
• Stop and go driving.
• Extensive engine idling.
• Driving in dusty conditions.
• Short trips of less than 10 miles (16 km).
• More than 50% of your driving is at sustained high speeds during hot weather, above 90° F (32° C).
• Trailer towing.
• Taxi, police, or delivery service (commercial service).
• Off-road or desert operation.
• If equipped for and operating with E-85 (ethanol) fuel.

NOTE: If ANY of these apply to you then change your engine oil every 3,000 miles (5 000 km) or 3 months, whichever comes first and follow schedule “B” of the Maintenance Schedules section of this manual.

NOTE: If ANY of these apply to you then change your coolant every 102,000 miles (163 000 km) or 60 months, whichever comes first and follow schedule “B” of the Maintenance Schedules section of this manual.

 

Note the word "usually" in the description of Shedule B. From the Ford owner manual that came with our trucks: "If you operate your vehicle primarily in any of the following conditions, you need to perform extra maintenance, as indicated. If you operate your vehicle occasionally under any of these conditions, it is not necessary to perform the extra maintenance."

 

My point was that one service schedule says do the diffs every 15k and trans every 60k, but the other doesn't mention them at all over a 120k schedule. Something ain't right. That's why I do the Schedule B. Even if your hard use isn't "usual" or "primary", where's the point of cumulative use where those things need service? None of it's hard and I consider it preventative.

 

My word for this type of maintenance is prudent. It doesn't matter much if one trades every 4 years, but it makes a huge difference in reliability when a vehicle is 15 or more years old.

 

I've seen friends of mine go way too long in between oil changes, run vehicles with low oil and run tires down to the steel belts on more than one occasion. Most people are ignorant about maintaining their vehicles these days. It seems rare to all of us because we are on a truck enthusiast forum. Therefore, we are not the norm.

 

If I bought a new or low-mileage vehicle with the intent to keep it beyond 15 years, I might do some extra service, paticularly items that show up on Sched B but not Sched A, but there's no data showing that is likely to make much difference in reliability. As you say, it's just prudent. At that point mechanical components are probably beyond their designed service life and some things will fail regardless. I've kept one vehicle 15 years and it was reliable with "normal"/Schedule A service. I think my average is about 9-10 years and normal service has served to keep them all reliable that long.