My parents have a 2024 Crosstrek and had to get the intake cleaned at the dealership after only 18 months because of buildup and a check engine light. They usually drive around 10 kilometers a day, about 20 minutes, and once a week they take a longer trip, but it’s still mostly city driving so the engine doesn’t get much load.
They really like the car, but they don’t want to keep paying for intake cleanings, especially once the 36-month warranty is up. They’re trying to change their driving habits a bit. Daily trips won’t change, but now they plan to take the car on the highway once a week to let it run longer and at higher speeds. We’re wondering if adding an air oil separator (AOS) would help reduce the buildup since this is a direct injection engine. If that won’t help, they’re thinking of selling the car and getting one with either port injection or dual injection.
Is there any other way besides changing how long they drive it? How long does a drive need to be to warm it up properly? Today it was 6°C outside, and when my mom turned the car off, the oil temp sensor showed 87°C. Is that warm enough?
@Ramirez
From what I know, high oil temps help because it burns off fuel that slips past the pistons into the oil. As for the carbon buildup, it seems that it just happens with direct injection engines.
@Lucypiper
Yeah, I figured that if oil temp is above 85°C and closer to 95°C then it’s warm enough. Their hope was that cleaning wouldn’t be needed until 4 or 5 years in, not after only 18 months. Maybe the weekly highway drive will help slow it down.
A catch can or AOS won’t really help here, no matter what the companies say. They can help with blow-by or moisture in the oil, but valve buildup is just how these engines are.
Donna said:
A catch can or AOS won’t really help here, no matter what the companies say. They can help with blow-by or moisture in the oil, but valve buildup is just how these engines are.
So how do people deal with it? Would a weekly 30–40 km highway trip slow it down? My parents expected some buildup eventually, maybe after 40–50k kilometers and several years, not after just 13k kilometers and 18 months. At this rate they’ll have to pay for expensive cleanings over and over.
@Ramirez
I actually removed my PCV system to help with this, but that’s a risky mod. Still, needing a cleaning after just 18 months sounds strange. Was that done under warranty? Did you ask for other opinions or quotes before agreeing to it?
Brady said:
Wait… driving for less than 20 minutes a day is a problem?
Short drives where the engine doesn’t get warm enough or stay warm can cause problems over time. Pretty much any car used this way needs more frequent oil changes.
It’s not really about engine load. What matters is that the engine reaches and stays at the right temp — over 180°F. Highway driving does that better than short city trips. An AOS can help a little with carbon buildup but won’t stop it. If you do get one, make sure it’s heated so it doesn’t freeze in winter.