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Recently I was driving my 2015 Subaru Forester a few hours from home and a "low oil" light came on. I drove to my destination (MIL's house, 10 minutes away), dropped off the family, turned the car off, then drove to a nearby mechanic (recommended by MIL). The light didn't come back on but I kept going.

The mechanic said the oil was a little low and that he topped it off. Since then (maybe a coincidence, maybe not) the car drives funny. If you step hard on the accelerator from 0, it gets very poor acceleration, practically nothing. If you accelerate a little bit first and then step hard, it's fine. Under certain conditions, it's not noticeable (highway driving with a merging lane to start with, or city driving with a lot of traffic). I wasn't even 100% sure that I wasn't imagining it until I got on the highway yesterday from a stop sign, with no merging lane, and had to pull back to the side because I couldn't accelerate properly.

My first instinct says that it's not shifting gears correctly (I have very little automotive knowledge). I don't know how a CVT works, or if even shifts gears at all. Any ideas what it could be? Could the extra bit of oil have caused this, or is it a coincidence?

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  • I think your hunch is correct. CVTs are basically gearless automatics using variable pulley sheaves under hydraulic control to transfer engine power thru the cvt to drive front and rear wheels. Your options are; dealer, independent Subaru cvt repair shop or xmission repair shop experienced in Subaru CVTs. CVTs are completely different xmission systems from electronically controlled automatics using multiple gears.
    – F Dryer
    Jan 3, 2023 at 19:43

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First off, CVTs do not shift at all. It could be a CVT issue, but I think there's other more likely candidates.

  1. Disconnected Sensors Check under the hood for disconnected sensors. TPS and MAF are obvious candidates based on the behaviour you describe, although I would expect the MIL (Malfunction Indicator Light, not your Mother-In-Law) to come on for those at some point.
  2. Bad oil/low oil Check your oil, maybe even get a cheap oil change (or a proper one if you are due). It could be that the mechanic added the wrong type or wrong viscosity of oil. Check the oil level also, I have seen mechanics way overfill the oil. Wrong viscosity or wrong amount can affect things like variable valve timing.
  3. Low compression Running without enough oil, in extreme cases, can cause damage to piston rings, leading to, among other things, lost compression. You can do a compression test for this (a tester is $15-20, or go to a shop).

This should get you started.

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  • Thanks for the suggestions. I was thinking about getting a quick oil change before doing anything else. I'll try to get that done tomorrow. Will report back after.
    – Matt
    Jan 4, 2023 at 20:06
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    Went for an oil change. Somehow I was 1.5 quarts over-filled. My guess is that the "low oil" light was not accurate, and then the mechanic I brought it to just put as much oil in as he could. In any case, with the proper amount of oil and a new filter, the car drives normally. Thanks.
    – Matt
    Jan 9, 2023 at 16:27

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