My warranty guide says I should replace the spark plugs at 30K and 60K, 90K. 120K. Really? Isn’t every 30,000 miles a little much?
I have a 2011 Outback, and I can see only two possibilities for your dilemma.
Either you are misreading/misinterpreting the official factory maintenance schedule
or
You are reading something that was supplied by the dealer’s service department, rather than by the mfr. (Hint: Be skeptical of most dealer service recommendations)
I will grant you, however, that the way it is printed in the factory maintenance schedule is–not well done. It lists spark plug replacement at 60k and at 120k for “2.5 liter Legacy/Outback/Forester; 3.0 liter, 3.6 liter, and Turbo”, and it also lists spark plug replacement at 30k, 60k, 90k, and 120k for “all others”.
The problem with that “all others” reference is that ALL Outbacks are either 2.5 liter 4 cylinder models or they are 3.6 liter 6 cylinder models. There are no “other” Outbacks.
So, no matter which Outback model you have, the spark plug replacement schedule is definitely 60k & 120k. The only “others” might be some Imprezas with a smaller engine, but I’m not even sure if they exist in the US marketplace. I think that all of the “others” are sold only in foreign marketplaces.
Does this clarify matters for you?