cytopath

When the engine is started from hot (left parked ~1-3 hours), I noticed that the oil light stays lit after startup for what seems like an eternity... about 1-2 seconds. I've noticed this only a few times, and each time the car had been parked for a few hours.

When starting from cold, it seems to me it usually goes out within 1/4-1/2 sec.

I haven't noticed this before in the 4+ years of owning the car, but it may be because I've never paid attention to it... Only on the first startup after changing the oil do I always watch the light, and without preloading the filter with oil it takes around 1 sec to go out.

Has anyone seen the light take longer than 1/2 sec to go out on startup? If this isn't normal, what could be the cause? Should I take it to the dealer?

RACER

Have you checked the level of oil lately?

cytopath

Yes, forgot to mention: oil has been full... it's currently 1 "x" mark down from the Full mark, which I don't consider low enough to add oil. I usually add around 200cc once it reaches 2 "x" marks down.

I'm using Mobil 1 10W30 since my first oil change at 3000 miles. The car has 41,500 miles on it and burns less than a quart per 3000 miles.

Anyone else seeing their oil light stay on for a sec or so after the engine has started? Does it last longer when it's hot after sitting a while?

RACER

I don't know if being 1-2 x's low has anything to do with your oil light, but you should never let the level go below 1 "x" mark.

Try topping it off and see if it still does it.

xviper

As long as your oil level is within the "X's", it doesn't really matter if it's always at the top. The car was designed to run perfectly fine even if the oil level is at the "add" mark. At this point, there is always enough oil to keep the oil pump fed and this is what determines your oil pressure and lubrication needs.
If the oil light stays on a bit longer after a hot start, consider some of the following:
-your oil pressure sender may be getting "lazy" with age.
-your oil pump may not be sealing as well as it used to.
-perhaps your oil is thinning out too much when hot (for whatever reason).

Do you have any noticeable leaks?

cytopath

Thanks for the response, xviper!

No, there are no oil leaks whatsoever. My garage floor is clean. Also, the oil being 1 X below full when cold shows exactly on the FULL mark when measured hot but after sitting 1+ hours (when I've noticed this happening), so you're right in that it's definitely not sensitivity being a few X marks low.

A few more datapoints, gathered tonight:

- When hot and restarted within 1 min after turning off, the oil light turns off almost instantaneously.

- When hot and left sitting 15-20 mins, the oil light goes out rather quickly (0.3-0.5 sec), but I've seen it flicker back on (flicker = almost not enough time to light the bulb fully) once about 0.1-0.2 sec after it went out!

- The light has never come on while driving, to my knowledge.

- When the engine is cold, I believe the oil light goes out rather quickly, but I'll need to confirm this tomorrow morning.

- When hot and left sitting for 1-4 hours, the oil light takes 1-2 seconds to turn off. Additional info just now: after leaving it for about 90 minutes, after it fired up I heard a fluttering sound while the light was on, which went away shortly after the light turned off. I nearly freaked out! It didn't really sound like valve ticking, even though in hindsight I think it was valve noise...

I change my oil with Mobil 1 10W30 every 3000-3750 miles, every time with a new Honda filter (the PCX 004 since it became available, P0H 305 before then).

Since I heard noise tonight at startup, I think it's an actual oil pressure problem rather than a bad sender. The oil was changed 2K miles ago and still looks somewhat clear, so I doubt the oil is deficient unless it's a bad batch of Mobil 1 (is this possible?!).

If the oil pump is not 'sealing', would that mean it would be leaking on the ground? Could it be that the oil pump is not pumping hot oil as well as before? Would that underperformance affect oiling of the engine during engine operation, or just at startup?

Is it a good assumption that the threshold for the 'idiot light' is high enough that having never come on during driving, it means that even during enthusiastic driving the oil pressure has been sufficient to fully lubricate the engine?

I have the Hondacare warranty, and will make an appoitnment with the dealer first thing Monday morning to look at the oil pump. However, I'm worried about real damage possibly having happened while the oil light has been on at startup (fluttering noise!), and during spirited driving while the oil pump has progressively been going bad. Are there tell-tale marks of such damage?

Anyone with a similar experience? I'd be surprised if I were the only one... How long are oil pumps supposed to last anyway?

xviper

When I talk about the pump sealing, this is internal. A poor pump seal would not necessarily leak to the outside. The oil pump comprises of driven "starred" wheel driving another mated starred wheel within an oil tight housing. It is the seal between the 2 wheels and the housing that I refer to. If the seal is not as good as it used to be, then pumping hot oil can show up as a lower pressure. Oil pumps can last the "life" of the car but has been known to fail prematurely.
I can't comment on the "fluttering". This description is too vague and could mean anything or mean nothing.
As for a bad batch of oil, I suppose it's possible but in this case, I'm inclined to think not. The more usual variation in batch quality would more likely be in the additives and Road Rage would be more the man to ask if this would affect pumping pressures.
To know for sure that the pump is functioning properly, your dealer can take various readings from the stock oil pressure sensor hole. They can also test that the sender itself is working within the designated range. It may very well be that the sender has become "tired" and require just a bit more pressure to turn the light off.
Insofar as it taking a couple of seconds to shut the light off, I wouldn't be too terribly concerned over this. Oil has an amazing ability to stick to metal surfaces for a very long time, so even a slightly lower than normal pressure for a couple of seconds at startup is not a big worry.

Greece_S2000

In addition to the above I would like to add another possibility . On most vehicles there is a one way valve or anti drain if you prefer that stops the oil from the lines and filter to drain back to the sump . It seems to me that this is a case of a stuck valve . I have to check the manual to see where this valve is located for the S2000 ( maybe in the filter too ) .

cytopath

Good suggestion, Greece S2000... I'll look this up in the service manual. Would a constriction in the oil pathway agree with all the observations in my post above?

Could this perhaps be due to a defective/clogged oil filter? Would this reduce the oil pressure only at startup or during the entire time the oil pump is operating?

Also, if the oil pump is failing prematurely, would that not affect oil pressure at all times? If so, why does the light never come on while stopped at a light, and why would it go out instantly when when sitting for only a few minutes?

Indeed, we might discount slightly the fluttering sound coming from the engine while the oil light was on, as I turned all other noises off and specifically listened for something due to my concern about this situation. It was weak, but definitely abnormal. It sounded like the sound you'd make if you whisper a long "ffffff" with a hard lingual "r" bouncing on the roof of the roof of your mouth. Coud it have been something in the valve train being low on oil until finally fed?

Finally, is it a good assumption that the car is safe to drive if the oil llight turns off at startup, albeit slowly? How low does oil pressure have to be before the oil light advises me of trouble while driving? Since it never does so, does it mean damage is highly unlikely? If it does occur, where would it show up first?

xviper

When it "flutters", what is the rpm reading?
I think you are prematurely worried about something that may not ever come to be.
I've seen oil pressure close 20 psi on a hot day, oil heated up to max, idling in stop & go traffic and no oil light, so I can only assume that the light won't come on till somewhere below 20 psi.
A clogged filter could restrict oil pressure as the oil goes to the filter after the pump before going elsewhere.
"IF" your pump is not sealing perfectly, it may take a second or two to "prime" it back up fully.
The engine's oil dependency goes up with rpm. Cold start up is also a very critical time for an engine because the oil has drained back down, but you're talking about a warm/hot start where the oil has not had a chance to do this.
Before you lose anymore peace of mind over this, get the pressure checked to ensure that part is OK.