Impreza oil light flicker at start-up

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Looking for input here, I'll try to give the most detailed explanation possible, and let users decide if this is a legitimate concern or a bout of automotive hypochondria.

Rundown:
2010MY Impreza 2.5i 5MT
42~ thou miles
Oil used: castrol syntec 5-30 / OEM Subaru filter. Last oil change I performed was 1200 miles ago. Oil level is perfect. No leaks, smells or consumption observed between OC's.

This is a close family members car. Perfectly maintained from new by my own hands. Oil changed early and often, OEM filters 90% of the time. Oil level always perfect. Always quality synth oils meeting recommended grade. I drive the car/look it over etc at least once weekly to assure everything is in order. I'm under the car monthly regardless for peace of mind.

Here's what has occurred:
When I started the car cold the other day, I noticed the oil light flickered after the engine started for ~1 second (at most).
-no engine noises accompany this
-at a hot/warm start light goes off immediately.
-once again, perfect oil level. No leaks. Filter is perfectly intact, no signs of damage.

I've consistently operated this car over the 3+ year course of ownership, and this is the first instance I have seen this. I likely would have noticed it had it been occurring at a time in the past. I have never observed this activity in any of my past subarus, including my 12 wrx with higher mileage in all my years of automotive ownership.
EXCEPT after i change the oil.

I'll also add, after i saw it i took it for a long drive to insure the oil was at least up to temp and idled for a while, staring at the cluster. No flickering at hot idle like other users have reported with pickup-tube failures.

-there is no conspicuous damage, contamination or obvious causes for the sensor to be grounding (or partially grounding out). I have personally seen dim/flickering oil lights on a old WRX after powerwashing the bay.
-DOES not occur on a hot warm start. Goes out immediately.
-If you cold start the car, it will briefly flicker. If you let it run shortly, turn it off and start it again, it will act "normal" with no flickering. (This is why I feel like it could be a faulty anti drain back valve in the filter itself.)
-charging system is in top shape. Battery is recently new. Cranks same speed as ever.
-idle is the same, no change in noise or drivability (that I can notice, I do feel like I have a pretty trained ear for automotive noises and I'm intimately familiar with this car)

Now, i'm curious if i'm overreacting or one of these hypothetical scenarios has taken place:

-cracked oil pickup tube? (Does it happen on these)
-bad ADBV on oil filter?
-other oil delivery related issue

Game plan is either to grab and oil psi gauge after work, or i'll have a reputable handy friend help me out and do a psi check.

I'll post a video shortly of the instance I spoke of. Ive witnessed it a few times, was not an isolated instance.

Please offer advice suggestions, also if any 08-11 impreza 2.5i owners would like to video a cold start as grounds for comparison, id really appreciate it.
 
When I have an opportunity, I'll post up a video and let other users be the judge if it would concern them or not.

Thanks.
 
Sounds completely normal to me. The filter may be draining back a little bit, but if the light goes off in less than a second, no big deal. A cold-start anti-drainback "problem" would be the light staying on for 3-5 seconds or more.
 
Whew thanks.. It flickers out over the course of a second or so. I'll get the video link up tonight when I have a chance.
That's the general consensus so far. I'm probably overreacting. It just certainly seems a new behavior, I'm guessing I should just leave it alone for now.. Not bother changing the filter or anything? (Like I said oil levels are perfect, no new engine noise that I can hear.)

I'm going to buy a gauge and check the oil pressure this week (need an excuse to buy a new toy anyway) just for peace of mind.
 
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What you describe seems common and not dangerous for these engines as they age a little, mine does it and has done since 60K.
The filter is vertical on this engine so nothing to worry about with the ADBV. IIRC the OP sending unit is below the alternator so it will be a PITA to do a mechanical OP test. it would probably scare you to death anyway at how low they can be at idle warm.

8-9 psi is common at idle warm but many of them are as low as 2-3 psi and they trip the light at warm idle. If it is not coming on at warm idle then i wouldn't worry about it unless it changes and does come on at warm idle and don't bother going to 40W it wont help this.
 
Originally Posted By: Trav
What you describe seems common and not dangerous for these engines as they age a little, mine does it and has done since 60K.
The filter is vertical on this engine so nothing to worry about with the ADBV. IIRC the OP sending unit is below the alternator so it will be a PITA to do a mechanical OP test. it would probably scare you to death anyway at how low they can be at idle warm.

8-9 psi is common at idle warm but many of them are as low as 2-3 psi and they trip the light at warm idle. If it is not coming on at warm idle then i wouldn't worry about it unless it changes and comes on at warm idle and don't bother going to 40W it wont help this.


Thanks for the advice and the info.
The sending unit on Third Gen Imprezas is right behind the alternator, visible and somewhat accessible. This model isn't a turbo so it's not horrible to get to. My WRX however, requires removal of the alternator AND a pair of model hands to access it (despite being virtually the same car)

Nope never saw it at warm start, nor warm idle (if it had showed @ idle, I'd be investigating ASAP. I'm already 'alerted' to what is very likely normal behavior.)
I also did my best to make sure the oil was as warm as (relatively speaking) reasonably possible and then sat at idle, with the cluster lights off at night and stared at the gauge in darkness to see if possibly I'd see a dim warning if there was an actual low oil pressure situation. But nothing. Only instance out of the ordinary is this 'cold start flicker' it's been doing lately.

thanks
 
This is the video I took of this occurrence the other day.

 
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My Pathfinder (143.5k miles) does the exact same thing depicted in the video on cold starts once in a while (even in warm Florida). It's done this with PL14610 and M1-110 filters. It never happens on subsequent warm starts. I'm not worried about it.
 
Thanks for all the advice.
I figured being a vertically mounted filter, a bad filter seems somewhat implausible (however I'm the farthest thing from an expert)

I swapped the filter for another OEM Blue filter just a little ago, and topped up the oil I lost in the process. I've been using these filters for years for 90% of the oil changes on multiple subarus I've owned and never encountered this issue before, so I figured I'd stick with what works.

I can't find an oil pressure tester locally, I'm planning a trip to Harbor Frieght this week when I have time to pick one up.

I'll keep the thread updated with my findings.

Thanks for all the feedback so far.
 
My guess is the oil pressure sender for the warning lamp is aging and out of spec. I wonder if it weeping at seal between the electrical contacts and sensor area?

In any case the lamp will at least do a check of itself for half a second which is normal so that extra half second or so is nothing to worry about. Forget it.
 
If that video is all it does, you're worrying about NOTHING! I didn't even notice a flicker until the third time I watched it. I was expecting the revs to come up half a second, and then a few flickers of the lamp... and then I was expecting to tell you THAT was normal. What you captured on video is truly nothing.
 
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