Why have to wait to add oil until at tbottom line?

[demarpaint]

Originally Posted By: Garak
Originally Posted By: demarpaint
In a case like a taxi driver I can see your point. Me, I figure if the hood is open and I have the oil, why not? Either way isn't going to hurt anything as long as the oil level is in the safe range.

Then, yes. When guys are adding a half a pint every day, it's like sheesh, don't bother.

Especially with the taxis, with the oil still flowing down, with the thing being off for less than fifteen minutes at shift change, you're not going to get an ideal reading anyhow.

If I only had to add a pint to the LTD, I would have been clicking my heels. When I opened the hood, I always had a litre ready.


The taxis are a totally different ballgame. I usually check my oil level after the vehicle sat overnight on level ground. No chance of overfilling that way, whatever was flowing down is in the sump. According to the owners manuals checking the oil level first thing in the morning is fine for my fleet. Fortunately I don't have to add oil to any of my vehicles during the interval. However in time things can change, so I pop the hood and check. Just because a vehicle can go the interval w/o adding oil doesn't mean it is going to stay that way forever. The last thing I want to do is drop my oil and find I was down over a quart.

 

[steve20]

Originally Posted By: 69GTX
If it's true that it takes 3,000 miles or so for the chemical tribofilms to build up after an oil change, then it's probably true that adding 1/2 to 1 qt of fresh oil near the end of an OCI could start to work on reducing the existing tribofilms. Maybe more so by topping off with a totally different add pack than the one you were running. Probably a fairly small effect. In any case, a potentially legitimate reason for not topping off during an OCI if you aren't quite to the add mark.


We took care of that potential problem when we had a 74 Chevy---we added the old oil from the Olds' oil change
Steve

 

[Garak]

Originally Posted By: demarpaint
The taxis are a totally different ballgame. I usually check my oil level after the vehicle sat overnight on level ground. No chance of overfilling that way, whatever was flowing down is in the sump. According to the owners manuals checking the oil level first thing in the morning is fine for my fleet.

That's it for me, word for word, too. I check on the level garage floor, after it's been sitting for hours. That way, there is no guesswork. I don't have to add, either, but it's obviously worthwhile to check. Things can go wrong.

 

[Linctex]

Originally Posted By: 69GTX
If it's true that it takes 3,000 miles or so for the chemical tribofilms to build up after an oil change, then it's probably true that adding 1/2 to 1 qt of fresh oil near the end of an OCI could start to work on reducing the existing tribofilms.


After Shannow and dnewton "Cage matched",
the conclusion was that it really doesn't happen.

Add a little if it needs it, it won't hurt a thing.

 

[Linctex]

Originally Posted By: steve20

We took care of that potential problem when we had a 74 Chevy---we added the old oil from the Olds' oil change
Steve

I had a '67 283 in a '76 shortbed (I bought it that way, I didn't do that swap!) that burned a quart every 50 miles.

It got fed a steady diet of old, used, black 30 and 15W-40 diesel oil!

 

[Silk]

My Volvo says 1.5 litres between the high and low marks, if I'm going to top up, I use a litre, I'm not interested in having small amounts of oil around. As mentioned previously, BMW Airheads will use oil to halfway between high and low, and stay there...top them up to the full mark, and they will go down to the same level again. I never bother to check mine between oil changes.

 

[DuckRyder]

It is probably because people don’t follow the other recommendations which may include:


Quote:
Switch off the engine and wait 10 minutes for the oil to drain into the oil pan.
Only add oil when the engine is cold. If the engine is hot, wait 10 minutes for the engine to cool down.
Do not remove the filler cap when the engine is running.


And over fill it.

Besides if oil needed to be added when it was between the marks, the area between the marks would be marked “add”... since it isn’t - don’t add...

Find something else to obsess about - like how the pyramids are actually alien landing pads and a sophisticated power transmission system as well, now theres is something to worry about...

 

[Ducman]

Originally Posted By: AnarchyX
So the manual says to not add oil if it is low until it gets to the bottom line.

Coming from the old school of keeping the oil level filled at all times, why is the car company (Ford in this case) saying to not fill it to the full line until it goes one quart low? And will something go wrong if I do?

It just doesn't make sense to have a "full line" if it doesn't have to be kept full.


The recommended process is straight forward, expedient and in that regard is fit for purpose.
Under normal operating conditions and assuming the engine is mechanically sound no harm will occur to the engine what so ever.
The engine doesn't have to be kept full of oil, but the option is there if you want to exercise your right.

As stated by others a policy of adding half a Quart of oil is also valid once the level on the dipstick gets to half way down to the add mark. It's just not expedient or convenient.

Once upon a time.
Ford used to spec and extra Quart of oil in certain high performance variants of engines.
The sump carried the same part number as the standard engine. The Dipstick tube was the same part number as well.
Guess what the only difference was? It was simply the Dipstick.
They had a different set of calibration marks that reflected the extra oil quantity.

In some applications a Dipstick reading is notoriously inaccurate and can be inconsistent/misleading necessitating a number of dips to get a plausible average reading and sometimes a very quick dipping action.
This can also be a factor when adjusting a smaller incremental amount of oil level as shown on a Dipstick.

Common sense must prevail.
If one has an oil burner then running at a lower oil level can be an advantage as well.

 

[Ducked]

Originally Posted By: Silk
I never bother to check mine between oil changes.


Then you'd better hope you never have an oil leak.

If I'd followed that (lack of) procedure, I'd have had a seized engine a couple of years ago.

I suspect this add-oil-by-the-litre/quart bottle is, at least partly, an American BIG SUMP THING.

I've read somewhere that the Daihatsu doesn't have much safety margin, and since the sump capacity is less than 4 litres (3.2 from memory but I don't have the manual on this PC) letting it get 30% or so low seems contra-indicated.

 

[Silk]

I have a slight pushrod tube leak, just a weep. I just changed to a POA/ester synth, so will be keeping an eye on my weep. I've owned the bike long enough to know what it does and what it doesn't.

That said....in the '70's I used to have some VW's...one car, one Kombi, and one engine. It had a slight pushrod tube leak, but didn't use a car much, my main means of transport was by motorcycle. When it was in the Kombi, I fitted a big tacho, and couldn't be bothered running a wire all the way back to the engine, and anyway, there was already a wire I could use, the oil light wire. The van was full of junk of course, and one night I heard a rattle in the back...I thought it was a couple of hubcaps knocking together. A few miles later it got really bad and the engine blew. I think maybe I should've checked the oil more often.

 

[Eddie]

This thread has produced more over-thinking responses that any I can remember. Ed

 

[Ducked]

Originally Posted By: Eddie
This thread has produced more over-thinking responses that any I can remember. Ed


That is because it originally challenged an under-thinking premise.

 

[Merkava_4]

I add oil 9 ounces at a time.