Check oil when engine is hot or cold?

wrote: (Honda Accord)

I get different dipstick readings when the engine has been sitting overnight vs. checking soon after running the engine. When is it best to check oil? ___________________________________________________

Check the oil at any time after the engine has been stopped for at least an hour. This gives the oil time to drain down and settle in the pan.

Rodan.

RTFM :-)

as for hot engine vs sitting over night. i don't think it matters much, just make sure you change the oil every 5,000 km or 3,000 miles

I have always heard that it should be checked in the morning or when you get gas, as the last thing before you start the engine back up. Most owners manuals don't say anything one way or the other. My new Nissan Altima manual says check it hot after waiting longer than 10 minutes & that's the first printed info I've seen on the matter.

Damn. What do you do when you gas up on the highway and check you oil? Get a motel room so you can wait overnight? Just gas up and then check the oil. That's plenty of time for it to drain down and give you a good reading. Just make sure you're not confusing the trans stick with the oil stick.

--Vic

I would say to just do it under the similar conditions each time, so someone can be aware of /changes/ in the level and appearance.

snipped-for-privacy@yahoo.com wrote in news:511ed7f5-faf3-4759-b2ba- snipped-for-privacy@m3g2000hsc.googlegroups.com:

This is a favorite subject of mine, and I've conducted extensive studies on it.

I have found that oil splash/pull up the dipstick tube, plus oil temperature, plus residual that has not dripped down yet, does definitely affect the dipstick reading. Also important is what part of the stick touches what part of the tube during insertion and removal, and this will vary slightly with each insertion/removal. I have even found that on my engine the dipstick will read differently from one side to the other, on account of the fact that the dipstick enters the oil pan at a slight angle.

If your oil consumption is normal (+4,000mi/qt), all you need to do is make sure you're well above the minimum level. For this, a quick check at the gas station is sufficient. If your consumption is high (as mine is; ~2,000mi/qt), and/or you're trying to determine _precisely_ what your consumption level is, you need to be far more rigorous. And this means checking first thing in the morning, before the engine is cranked, and with the car sitting in the exact same attitude for each check.

The comparative validity of any measurements lie in the consistency of method from instance to instance.

It isnt that critical... You need to be above the fill line, and below the overfull line. This is not rocket science.

I never said it was rocket science. But atleast twice in the 250K miles I have owned the car. A measurement a few minutes after engine is stopped yielded a measurement slightly below the lower mark. And when I let the car sit overnight, the measurement was slightly above the mark. Both times I checked each measurement atleast twice to confirm. Both times I was on level ground. This was very strange and I just wanted to know what could be the cause behind it.

A: Because it ruins the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail?

snipped-for-privacy@yahoo.com wrote:

This was very strange and I just wanted to know what could be the cause behind it.

It isnt strange at all. Oil expands when hot and contracts when cold, but also the engine parts do the same. There will be some volumetric diffences due to temperature.

Mainly the oil will drain out of the remote crevices overnight and it may give a reading that is slightly more than a short stop reading.

Now, if you are using something like Amsoil and change it only infrequently, you may see large differences. I have seen some of this crap that is so viscous you need to drain the engine for a LONG time just to change the oil. Otherwise a 5 quart fill may give you 5 and a half quarts in the crankcase.

If your problem is that it shows slightly above or slightly below the fill mark, the answer is the same - add some oil.

You want it to be well into the gap between fill and max whenever you check it. Small differences due to temperature expansion/contraction or weirdness with the oil filter bypass don't count.

Hide quoted text -

Check your oil first thing in the morning before you start your motor. Make sure you are on level ground. Just pull out the dipstick and look at it. No need to wipe it.

If there's a noticeable change in how fast the oil drains down from the heads it might be worth looking for clogged oil passages. Think that was a problem with some Camry heads, and it could happen with any car with lots of miles. Don't have enough info to know if that change in draindown time happened.

--Vic

The Amsoil situation I quoted was on a little import type pickup (dont remember the maker at present), and the owner went 12-14,000 miles between changes. When I changed the oil on it, I couldnt believe how viscous and mucky it was. When it stopped draining, I replaced the filter, and refilled the crankcase with the "correct" amount of oil....and found I was a half quart too full. I should have let it drain for several hours, it turns out. But no harm done.

I wouldnt run that crap, nor that change interval, in anything I own.

Some heads that I can remember did have smaller than optimum drain holes. In particular, the 2.5 litre Iron Duke gave me some problems with oil leakage around the valve cover gaskets because it would not drain properly. I "fixed" that by opening the drain holes with a grinder, and machining the head sealing surfaces flat (they were cast, rough, crappo pieces). Then I installed a cast aluminum valve cover for rigidity and the problem was solved. But, you never solve all the problems with that particular engine.

What does the "FM" say these days? When I learned how to drive, the procedure was to:

1) start the engine when it is cold 2) let it run for 1 minute 3) shut it off 4) check the oil 1 minute after you shut it off

Is that still the current ideal procedure?

In reality, as long as you are not too high and not too low, you are probably OK, so it likely doesn't matter too much how you check it.

-john-

"John A. Weeks III" wrote in news:john- snipped-for-privacy@comcast.dca.giganews.com:

That makes no sense.

Why would you run settled oil through an engine that's of variable ambient temperature, allow the oil to drip back down into the pan at some indeterminate and variable rate, then attempt to measure the variable product of your activity?

If your oil consumption is normal (+4,000mi/qt), all you need to do is make sure you're well above the minimum level. For this, a quick check at the gas station is sufficient. If your consumption is high (as mine is; ~2,000mi/qt), and/or you're trying to determine _precisely_ what your consumption level is, you need to be far more rigorous. And this means checking first thing in the morning, before the engine is cranked, and with the car sitting in the exact same attitude for each check.

The comparative validity of any measurements lie in the consistency of method from instance to instance.

Never heard that one before & I've been driving for 43 years. Where did you hear this procedure? It really is non-repeatable engine to engine, varies with temperature, etc. Lots of reasons this is not an ideal procedure.