Hello! Subaru Outback 2015 with ~113,000 miles. I’m really behind on the schedule and have not gone in for regular service in a couple years. I change my own oil and filter, and I have a mechanic friend who changed my brakes recently. Wondering what services I should ask Subaru to do when I take it in this week? I’m pretty sure the transmission should be flushed, but what about all the other things on the maintenance schedule that I haven’t done previously? Replacing anything, or more so inspection? Thank you so much.
Overdue on maintenance schedulewhat do I have checked??
- Thread starter avh
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Ditto on the owners manual. Transmission is a lifetime fluid unless you use the vehicle for towing. Spark plugs every 60k require removing motor mount bolts and lifting the engine. Coolant at 110k, but 113k wont hurt it, just drain and fill, do NOT flush. Engine air filter every 30k, cabin air filter every 15k (DIY)
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Gear box lubes too.
Flushing is an opportunity to allow contaminants into your cooling system. The engineers who designed your vehicle took into consideration the properties of the various metals in the engine and how those metals interact with each other. The coolant provides a connection between the various metal and because it does, there is a path for dissimilar metal corrosion. They developed a coolant formula that provides the maximum protection all the various metal parts that inhibits this dissimilar metal corrosion.
The engineers also developed a maintenance schedule that will remove most of the spent anti-corrosives and replenish them with enough new anti-corrosives to protect your system until the next scheduled change. The few remaining spent anti-corrosives will not harm the system because from day one, your vehicle has been generating spent anti-corrosives. Draining and refilling the coolant per schedule will dump about 85% of the spent chemicals and replace them with fresh. The first recommended change (2014 Legacy schedule) is 11 years or 110k miles. They also left in a buffer of around 20% for those who go a little longer than they are supposed to.
At this point, your current coolant has kept your cooling system perfectly clean. Using a "flush" chemical would not do anything good, but you would be hard pressed to get all of the flush chemical out of the system and in my experience, flush chemicals are very hard on rubber hoses and seals, very hard. In case you didn't know, there is a rubber seal between the radiator tanks and the radiator core, you don't want that to blow.
A plain water flush, unless you use purified or distilled water, WILL leave some foreign minerals. You will never get all that tap water out either so there will be minerals that will interact with your anti-corrosives and reduce their effectiveness. Hard water minerals will immediately start bonding to the metal surfaces inside your cooling system and start reducing its effectiveness.
A flush machine could have remnants of other types of anti-freeze in it and sometimes, different anti-freezes don't play well together. Plus at your stage, this is completely unnecessary even if done at a dealer where their machines are not contaminated.
Bottom line, your cooling system is in perfect order, the current coolant still has some life left in it. Draining and refilling it with the factory premix will effectively reset the system to what it was at about 20k miles and two years old. The recommended second and subsequent cooling system services are shorter to compensate for this. Follow that schedule and your cooling system will always be factory fresh (with some miles on it). Sometime around the 20 year mark, you should probably change all the hoses and thermostat and maybe even the water pump.
