Oil pressure light stayn on a little longer these days

[EtaSport]

When I start the car in the morning, I notice the oil pressure light stays on for a little while longer then it used to. It used to light up for a second or so and go right off after the engine cranked. Now it stays on for probably a good 3 seconds after it starts.

It never comes on at any other time, not at idle, hot, cold anything. Im thinking the pump is just not building pressure like it should (stock pump w/approx 400k), but should I worry about it? I dont run the engine that hard, but it gets a lot of city and highway mixed driving. It has been running like a top with no issues. Im running 10w40 just changed about a month ago with bosch filter.

[MrK]

Oil pressure light tends to stay on a bit longer at start when the oil level is below max. Check your dipstick, and see if your oil is at the top line or not.

[DaN]

Maybe the new filter doesn't have an anti drainback valve.
I had some Mann filters that didn't appear to have them.

[arsevader]

Maybe the new filter doesn't have an anti drainback valve.
I had some Mann filters that didn't appear to have them.

Possible though I use Bosch filters and they seem to have the valve.

[T.Dot E30]

Did you change to a different grade oil recently?

That could be it, or it could also be the cold weather.

[arsevader]

Did you change to a different grade oil recently?

That could be it, or it could also be the cold weather.

Cold oil produces more pressure though, not less.

[EtaSport]

Always use 10w40 havoline. Always use bosch filter, level is correct. Does not stay on when weather is cold out, more pressure as stated above. Plus it has been warmer here the past few weeks. The motor is old, I suppose I should be happy with its performance thus far.

[AdamF 88iS]

Swtich to 20-50.

[EtaSport]

Swtich to 20-50.

Been in the back of my mind. I may try that next oil change.

[T.Dot E30]

Cold oil produces more pressure though, not less.

Where did you get that from?
In lower temperatures, the oil becomes ticker and doesn't move around as good.

Put a bottle of oil in the freezer for a day, and take it out and see how slowly it pours out.

Now put it in the oven, run it under the hot water, and see how easier it pours out.

But of course, it depends on your definision of "COLD".

It colders temps, close or below freezing, it takes longer for the oil to heat up and build pressure, hence the reason thiner oil is used in colder temps.

[EtaSport]

w-winter designates the oil flow in cold temperatures. a 10w40 oil will flow like a 10 weight viscosity in cold temperatures, and and a 40 weight viscosity at warmer temps.

[arsevader]

Where did you get that from?
In lower temperatures, the oil becomes ticker and doesn't move around as good..

Don't confuse Viscosity with Pressure. Just because the oil is slower moving and hasn't reached all the parts of the engine doesn't mean that the pressure isn't high. In fact thicker oil produces higher pressure. Add to that, tolerences are tighter on a cold engine.

Think of it this way. Try sucking Water through a straw, then try sucking Molasses. The thicker Molasses requires more suction therefore more pressure.

Try running a 0W-5 oil and see what happens. Your oil pressure would be non existant on an engine such as an M20 with many miles on it.

[motorprestige]

Run 20W50, I use castrol GTX high mileage. I also run a cleaner through with my old oil before every other change. I have 232,xxx on the original engine, but i have been looking at a nicely rebuilt head, perhaps with a slightly lumpier cam, and maybe some light porting/polishing.