Subaru Service: What’s really necessary?
How should you service your Subaru? You could follow the recommendations in Subaru’s maintenance schedule, which you can find in your owner’s manual or online. If you want to keep your warranty, it’s the minimum that’s required.
But is the maintenance guide the best way to keep your Subaru in good shape and avoid major repairs? It’s a hard question to answer because what’s “best” varies from person to person. People have different goals.
Subaru’s service recommendations
Representatives from Subaru aren’t in the habit of calling me to discuss their strategies, but I think I have a fairly good idea what drives their maintenance recommendations. First, Subaru doesn’t want their cars to break down under warranty, so I think it’s safe to assume that following the service recommendations in the owner’s manual will keep the car in good condition for the first three years of its life. Second, Subaru doesn’t want the car to appear expensive to own. If they add too much to the service schedule, people who check for total cost of ownership before buying a car won’t want to buy a Subaru.
You may want to service your Subaru more often than required
I’m sure you don’t want your car to need major repairs under warranty, just like Subaru. But what about later? Subaru’s longevity goal may only be 5 to 8 years. They’re in the business of selling cars. They’d certainly like you to buy a new one. Consumers can be influenced to buy a new car with the “carrot and stick” approach. The “carrot” is all the new features a newer car will offer. The “stick” is the increasing cost to repair your Subaru as it ages, especially if it’s poorly maintained.
You should think about what you want from your car and make a plan. You may want to drive your Subaru for 15 years and 200,000 miles. In that case, you’ll probably want do more than the minimum. On the other hand, maybe you like getting a new car every so often. If you want to get a new car every 3 to 5 years, following the maintenance guide will likely be enough.
Our recommendation for your Subaru Service Schedule
As we see it, our job is to advise you so you can reach your longevity goal, whether it be 80K or 300K. We have plenty of work, and you’re not going to hurt our feelings or pocketbook if you don’t take our recommendations. If you’d like to stick with the minimum, that’s OK. If you’d like to do everything you can to make your car last as long as possible, we can do that too.
Occasionally we’ll feel strongly that a maintenance item is very important, but it’s your car. Once we’ve given our opinion, you’re welcome to do whatever you think best. Since only you know your situation, how could we possibly know better?
Our recommendations are based on what we’ve seen work over the last 40 years. We’re pretty sure our recommendations are valid based on the large pool of anecdotal evidence we’ve amassed over the years. However, not everyone agrees with us. If you call around and compare, you’ll find that a 30K service will be a little bit different at every auto repair shop.
You might think that going to a Subaru dealership will guaranty a consistent service recommendation, but it won’t. We’ve seen some of the worst examples “wallet flush” items on dealer invoices. Each dealership is an independent franchise and they have wildly different cultures. Some are great. Some are scandalous.
Your Subaru service plan should at minimum include what’s in the owner’s manual. You’ll need to use some critical thinking and decide who to trust for any additional recommendations.
Below I’ll list each service item, when the manufacturer recommends it be done, and then when we think it should be done. When there’s a difference between the manufacturer’s recommendation and ours, I’ll explain why.
Subaru has adopted a 6,000 mile interval for motor oil. I should mention that there is no interval that requires only an oil change. The wheels should be rotated and brakes inspected every 6,000 miles as well. This is one of reasons why maintaining your car at a quick lube shop is a bad idea.
6,000 miles is a weird interval, and some of the new Subaru engines tend to consume a lot of oil. Maintenance schedules have three general categories of service: small, medium, and large. A typical service schedule would be — small, small, medium, small, small, large, and then it repeats. When the 6K interval is used, the medium size “15K” type services don’t fit neatly into the pattern with large services at 30K. We recommend changing the oil every 5,000 miles, just like Toyota recommends.
Subaru recommends replacing the cabin filter every 12,000 miles. This is overkill in our opinion unless you park your car under a perpetually shedding tree or just got back from Burning Man. We recommend every 30K miles. Will this void your warranty? It shouldn’t, but it’s not my call. The only damage a clogged cabin filter could possibly do is to the blower motor, so unless the warranty claim is for the blower motor, I don’t see how a failure to replace the cabin filter on time could be used as an excuse.
Engine air filter
Subaru recommends replacing the engine air filter every 30,000 miles. We agree. This is a good interval for most people.
Subaru recommend replacing brake fluid every 30,000 miles. We agree. While brake fluid degrades more with time than miles driven, putting brake fluid on a time-based schedule only leads to it being forgotten. 2-3 years is a good interval for brake fluid and an average driver will drive around 30K in 2-3 year.
Subaru’s recommendation for differential oil makes no sense at all. If you drive under “severe conditions”, you need to replace the differential oils (front and rear) every 15,000 miles. Otherwise, you never need to replace it. They recommend inspecting the oils every 30K, but gauging the condition of differential oil is quite difficult for some models. It can’t be tested like brake fluid or coolant, and it doesn’t change color or smell as it degrades. The amount of debris in the fluid is a useful metric, but metal powder settles to the bottom of the sump and typically won’t be seen when the fluid level is checked at the fill hole, which is at the top of the differential.
We recommend replacing the differential oils every 30K miles. 30,000 miles has been the interval for gear oil on Japanese cars for years and years. The fluids and gears are the same as they’ve always been, and there’s no reason to change what works. There are more limited slip differentials these days, but if anything, they require more maintenance, not less. Several Honda products with limited slip differentials require fluid changes every 15K.
Another one of Subaru’s service intervals that makes no sense is for the CVT fluid. Subaru says CVT fluid never needs to be replaced, unless the car is driven under “severe conditions”. In that case, it should be replaced every 25,000 miles.
We recommend replacing the CVT fluid at least every 60K miles. If you want to take really good care of your car, consider replacing the CVT fluid every 30K miles. The truth is that we don’t know the best interval. CVTs on Subaru cars is a relatively recent thing. They’ve had quite a few problems, but there’s no way we can know for sure if more frequent fluid changes would have prevented these failures. It seems likely that it might, and common sense dictates that no type of oil can last forever. 60K seems like a conservative balance of cost and likely benefit to us.
Subaru has a number of engines that require periodic valve adjustment. We generally recommend just following the recommended schedule, which is different model to model. We’ve seen some WRXs that develop tight valves early, but for the most part, they make it to their interval. There are a few cars like the Toyota Tacoma with a 2RZFE or 3RZFE and the Gen1 Honda Fit where we recommend valve adjustments more frequently that the manufacturer, but so far this hasn’t been needed for any Subaru models.
Subaru usually recommends spark plugs at 60K or 105K depending on the model. We haven’t seen any reason to modify this recommendation.
If the car has a timing belt instead of a chain, then we recommend replacing it during the timing belt replacement. Otherwise, Subaru recommends replacing it the first time at the nice round number of 137,500 miles, and then every 75K after that. Coolant is getting a little tough to advise on. In the old days, every 30K was a good interval. Now all of the Japanese manufacturers use “super long life” coolant, and it actually seems to hold up pretty well. If you have a car without a timing chain, I’d recommend no later than 120K, but I’m far from passionate about it.
Subaru recommends replacing the camshaft timing belt at 105K. We haven’t seen any reason to change this recommendation, but we also recommend replacing a bunch of additional items at the same time. If any of these items fail, the timing belt will need to be removed again, and some of them could lead to engine failure if they fail.
- The water pump. The water pump is driven by the timing belt and is extremely unlikely to make it to 210K without failing.
- The cam seals, crank seal, and oil pump o-ring. Sometimes they’re already leaking, but even if not, we recommend replacing them at the same time as the timing belt.
- Tensioner, pusher, and idler pulleys. These don’t require any additional labor on most models and can cause the new timing belt to break if they fail.
- Drive belt(s). These can be replaced later without repeating the timing belt job, but they need to come off to replace the timing belt, and like the timing belt, they’re likely in need of replacement at 105K.
Service your Subaru doesn’t need
“Wallet flushing” is the term mechanics use to describe services that do little or nothing for the longevity of the car, but do bring in money. If you’re offered any of the following, it should raise a red flag.
- Injector cleaning. On-car injector cleaning machines don’t do anything beyond what adding a can of injector cleaner to the fuel tank would do, so there’s no reason for this service to exist. Do injectors get dirty and clog? Yes. Sometimes, on some models of cars. An occasional can of Techron or similar might help prevent it. However, to fix an injector with low flow, it needs to come off the car and be cleaned in an ultra-sonic tank. Removing injectors for real cleaning is a waste of money unless there’s a problem, like a P0171 lean code. If you’re offered an injector cleaning with an oil change, save your money. The best you can hope for is some psychosomatic improvement.
- Felt battery terminal pads. These are offered to prevent corrosion on the battery terminals. They don’t work, and some folks charge a whole lot of money to install them. If terminal corrosion is a persistent problem, there’s something wrong with the car or battery.
- Transmission additives. For the most part these are a bad idea. There was a product called Lubegard that we used in the early 1990s to free stuck shift solenoids, and it worked fairly well for that purpose. However, it’s a bad idea to add anything but the correct transmission fluid to a working transmission. Surprisingly, some dealerships seem to love this kind of stuff, even though it could void the warranty.
- Cooling system flushes and additives. Flushing the cooling system is unnecessary. Simply draining and filling the coolant and then bleeding the system is all that’s required. There are a myriad of other cooling system additives that go along with the system flush and they should be avoided. There is one additive that should be added to Subaru coolant called Subaru cooling system conditioner. It’s a stop-leak product and it’s used to help seal Subaru head gaskets.