After review the maintenance history of my 4Runner from before I bought it, it is possible that some things missed a service interval. Below is how long I think those things went between servicing. (Toyota suggested service interval in brackets.)

Spark plugs, diffs – 50 k mi (30 k)
t-case and coolant – 44 k mi (20 k)
tranny – 90 k (60 k)

I am generally pretty easy on the truck. Minimal city driving (no commuting), mostly highway miles, a fair bit of mild (gravel roads) to moderate offroading but mileage wise doesn’t add up to much. I don’t tow. I live in a moderate climate, never below freezing, never hotter than 75ºF, I park in a garage. Engine oil was always done on time (6 k between changes the odd time.)

I will also point out that the time interval was greatly exceeded as well, because the truck spent almost year on the dealers lot before I bought it.

Is this a big enough deal that I should worry?

I don't know for sure what was or wasn't done. Here is the full story:

I have owned my 4Runner for 2 years now. I bought it certified from a local Toyota dealership with 57,000 miles on it. Several months after purchasing it (@ 60k) I brought it in for servicing. According the maintenance schedule it was due for a big service at 60,000 mi. The service guy told me that all that stuff was done by them prior to me buying it, that all I needed was an oil change. Great! I was expecting to pay $500 or so changing diff and t-case fluids, spark plugs, coolant flush, tranny flush etc. (Thinking to myself that in pretty honest of them to tell me that when I asked them to perform the full 60 k mile service.)

20 k miles later when I was ready for another diff / t-case fluid change and coolant flush (thinking it had been done at 57 k when I bought it) they said it wasn’t time yet, but that it was time for the spark plugs. Seemed a little odd that their recommendations didn’t line up exactly with Toyota official maintenance schedule, but I didn’t fuss over it. As it turns out they were not even able to change the spark plugs because the coil bolts were rusted on. Over the next few weeks I worked on getting the bolts freed.

The following service, which was yesterday at about 84 k miles I reminded them to change the plugs (they seemed to think that was already done previous service). I also asked them to do the diffs/t-case and coolant. Again, they didn’t seem to think it was due yet, but I insisted anyway. I told them that I thought it was last done at 57 k and was overdue. They went through their records to check, and according to them, the plugs were last done at 34 k, the diff/t-case and coolant at 40 k, making me way overdue! As it turns out, they were not able to get the drain plugs off either front or rear diff because they were rusted on. I will work on them with penetrating oil and hopefully they will succeed next service.

The rusted coil bolts and drain plugs lead me to believe plugs and diffs were not done at 57 k. I can only assume neither were the coolant or tranny.

I'll get the tranny done next time with the diffs.

So are you supposed to change the plugs every 50k, transfer case and coolant every 44k, and tranny every 90k?

I too purchased my 2005 4WD SR5 Toyota certified from the Dealer. I bought it 1 yr ago with 47k on it and now have 68k on it. I been doing my own oil/filter changes every 5-5500 miles with Castrol syntec (what the Dealer always used) and a oem filter, but never worried about the other things to much b/c it was my understanding that when they sell you a certified vehicle with the remainder of the 100k warranty on it they change everything for you even if it does not call for it. So am I to take this not has true? Should I be changing what I can and let the Dealership do what I can't or.....

Any help would be appreciated.

Thanks
Judd

This is Toyota's recommendation when you get to 70k. Toyota Parts and Service

Toyota's recommended intervals are for normal operating conditions: for the spark plugs V6 at 30k; V8 at 90k. Coolant at 100k. Transmission fluid is suppose to be lifetime. Maybe I missed it, but I didn't see a recommendation from Toyota for the transfer case or diffs.

On mine, oild change at 4500. Plugs, diff and transfer case at 30k. Transmission at 60k. Coolant at 90-100k.

Not sure what they do during the certification process for pre-owned.

The OEM V6 plugs are supposed to be changed every 30K.

Coolant is supposed to be changed for the first time at 100K miles for '04 and newer 4th gen 4Runners because they were factory filled with that Super long life coolant. Unfortunately, even though '03 was the first year of the 4th gen 4Runner, Toyota didn't use the super long life stuff until the '04 model year.