204k miles - just realized 2WD has rear diff oil

This is kind of embarrassing, since I've always tried to be pretty good about maintaining my truck. 2006 2.7L RWD base model @ 204k miles - I've had it since it was brand new. Mostly highway miles and lots of road trips.

I thought I had all the maintenance items covered more or less, and always thought diff fluid only applied to 4WD models. I do most of my own maintenance, including having done a number of DIY/repair items including disc brake pads, coolant bypass pipe replacement, valve head cover gasket replacement, spark plugs, .....

I guess I have two questions:

At this mileage, does anyone have an idea how much damage or excessive wear has possibly been done by never replacing the original diff fluid?

And, am I missing any other maintenance items besides the ones I've been staying on top of, including:

• engine oil, ATF, brake fluid, power steering fluid, coolant
• air filter (engine and cabin)
• drive belt
• spark plugs
• shocks

I don't like to rely solely on the owner's manual since the recommended service intervals don't really go beyond 100k or so (IIRC), not to mention back then they made the ridiculous claim about the ATF being 'lifelong' or some nonsense.

I've been thinking about replacing my water pump, O2 sensor, and thermostat as preemptive precautions, but I understand those are more 'pass/fail' items that just work, or they don't (opposed to the bulleted items, which degrade in performance over time).

I do need to check out my rear drum brake shoes soon.

 

Meh. Maybe some, maybe not a lot. Change it, look for glitter in it for your own amusement, and keep rolling. Not difficult to do. Make sure you can get the fill port open before you pop the drain port.

Definitely a case of "better late than never". The rears in these trucks are extremely robust and it doesn't seem like you've been hammering it.

 

You're doing pretty good if you're still on the OE waterpump at 200K. Probably didn't do any appreciable damage to the 3rd member if it's still working quietly and smoothly, I wouldn't loose any sleep over it. Swap out the gear oil, make sure the old oil isn't full of shavings. If that were my truck I'd probably preemptively swap the water pump with those miles, also the thermostat belt and possibly idler pulleys if needed. Mine lasted 150K and then the pink crud started building up behind the wp pulley so I had warning and was able to swap it before it was a problem. Personally I like doing that type of maint stuff before the part goes sideways, much less drama. The motor's mechanical noise really quieted down with the new pulleys, it's one of those noises that builds slowly over years and isn't very noticeable until it's gone.

 

Doesn’t matter when the diff oil was changed. It needs to be changed.

the vehicle drives. Therefore there isn’t a problem.

step 1 in writing up a concern is there being a concern. As well as duplicating and verifying it. Doesn’t sound like there is one.

most people do this to most cars, but continue on without changing it.

 

Just change the diff oil and don’t worry about it. There may not be any “damage” to the diff. At this point there’s nothing more to be done, just drive it.
Some may disagree but I would replace the water pump. Most of them will fail somewhere over 100000 miles and under 200000 miles. Mine failed at 110000 miles. Yes some will last longer than 200000 miles but that’s a small percentage. It’s going to fail sooner than later so replace it now and avoid over heating your engine. Replace the thermostat when you replace the pump.

 

I changed the transfer case and both diff's oil at 170,000. I'm at 255,000 now. The garage I use told me to bring it back and they'd do it again at 300,000.

 

Really, that first change is the most important one and it will likely look like crap.
After the gear wear in and you change the fluid, it tends to stay clean quite a bit longer.
Let us know how it looks.

 

Good info here guys, and thanks.

I have read in the past about water pumps failing and figured the time for mine is likely nigh.

Is the thermostat easy to get to when you replace the wp? I just did the coolant bypass pipe replacement about 6 months ago (swapping the old plastic pipe for steel). I think the guy that did the write up on here replaced his thermostat, but the details weren't really there. I know the front end of the bypass pipe sort of butts into the thermostat.

I knew I should have replaced it then, but I was in a bit of a rush and going for 'cheap'....though I did it all with OEM parts.

 

You've stayed on top of the really expensive parts (engine & transmission). I think the rear diff will be fine, but good to start changing the diff fluid. If the rear diff is damaged, which you'd likely know because of noise, the good thing is rebuilds aren't terribly expensive and are easy to install.

My only addition to your list above would be PCV valve... cheap and easy to replace. (at least on the V6)