Topic: Oil change: how much truth there is in "conventional wisdom"?

[Raul CB750K1]

You know, conventional wisdom is what we hear from somebody we think is knowledgeable, and we assume it to be true but it doesn't stand common sense -like "running low on gas is bad because the carb sucks all the debris", like if the point where the gas is sucked changes depending on the amount of gas.

So I was riding my bike after work yesterday thinking about changing the oil in the afternoon. I was doing a mental check: oil - check. copper washer - check. Filter - check. And was mentally going through all the procedure. Start the bike and let it run for some minutes to let the oil get thinner etc. And that's when I realized: "wait a moment". So I'm going to park the bike after a 20 mile ride, the oil won't be hotter than this. It will sit for three hours, so plenty of time for the oil in the head to go back to the oil pan, and it won't be thinner than now. And this will happen EVERYTIME you park the bike after a ride. Let it sit and all the oil that can go to the oil pan, will.

So, the only difference in drainage will be how much of the old oil remains stuck in the oil sump walls because of the oil temperature, something than in my opinion is negligible or that can be compensated by leaving the oil drain for a few minutes more, say the same time that you would leave the bike running to warm the oil -but you save on gas-.

Furthermore, when I changed the filter -I forgot to mention it is a modern Suzuki GZ250-, last time the filter housing was full of oil for having warmed the oil. This time, as it had time to drain, it was empty and therefore much less messy.


So, is it the "warm the oil" conventional wisdom right, or doesn't make sense at all?

[333]

Okay, I looked at the title of this thread and said, "not another oil thread?".  But you've hit one here.  This theory seems right on.

[troppo]

I reckon you have too much thinking time on your hands raul 
Its a very interesting point though

[SteveD CB500F]

My ex-boss had an excellent phrase for this. He called it "Ancient Spanish Tradition" (yeah, thought you'd like that Raul...)

If the answer to the question "Why do we do it this way?" is "Because we always have", then you have one (a tradition that is).

[Buber]

It's all valid, but..... just the last drips in the oil pan - if the oil would be hot, it would pour out easier from the pan. Otherwise, little bit more may stay in the oilpan - but that's the only negative point I can find in this line of thought....

[Gordon]

I don't normally bother to run the engine and warm the oil before changing it, but that's mainly because of a certain amount of laziness and not because of any disbelief in "conventional wisdom". 

[Bob Wessner]

I've looked at it this way. As you said, it won't be any hotter or thinner than after a ride, so that's when I do oil changes. Things can be hot, but I use a pair of those mechanic's gloves with the rubberized palms and fingers so I  have no problem with the heat.  After draining what comes out on its own, I kick it over a few times to get the remaining couple of ounces of the oil pump.

I've noticed, and I'm sure others have as well, it takes a good deal longer to warm these engines up than you might think if you are going to do a cold start prior to an oil change, they're cold blooded for sure.

[Johnie]

Raul...your wisdom is like a full head of hair, the more you brush it the more it comes out.  I think you may be onto something.   

[Raul CB750K1]

I reckon you have too much thinking time on your hands raul 

I don't devote time to thinking, it just comes naturally while doing other things, like i.e., riding a bike. I just thought that warming the oild didn't seem to give more benefit than the annoyance it gives, so I decided to share that thought with you all in case there was something that escaped my reasoning.

Steve, I liked that. Ancient Spanish Tradition...., I like it. 

[goon 1492]

+1 on that, I even in my trucks I let is set for a minute or two when draining, drain it and let it set while i get a drink and a smoke, and then proceed with the filling and when i fill them  back up i let the oil can set and get all the drippings i can out of it and into the motor; I know its not much more than a thimble in each can of oil but in two or three quarts of oil it can add up.

[crazypj]

In the shop, if we were doing valve adjustments we wanted a 'cold' engine so oil plug got removed and only re-fitted after service was done and before carbs were adjusted. (probably an hour or more drain time)
 Leave the plug out of engine so if you do put oil in, it lets you know you forgot something  . ( making a mess is safer than blowing an engine )
 I've seen happen where plug was only fitted finger tight and fell out later or engine was started without any oil.
PJ

[Tower]

Raul, you've started a discussion that has been on my mind for awhile also.

So, I'm going to add a little more controversy: Consider the opinion of the Shell Oil exec who claims oil changes are not necessary - merely topping up the oil can suffice to extend usage.

What that means; is getting every last drop out before adding the next batch is wholly unnecessary - making preheating even further unnecessary.

Since oil changes have become somewhat of a "religion" in maintenance schedules (and there is an oil-change ritual that goes with it) , this convention is all the harder to give up.

[bradweingartner]

I VERY rarely completely change oil on any vehicle I own. The reason is simple.

It's not necessary. Furthrmore, I have not suffered a single engine failure due to not changing the oil. Not changing leaking oil seals? Not changing timing belts? Not putting th piston wrist pin circlip ALL the way in? Yeah, that will do it.

But oil, I'm just not going to change it religiously because I've never done it and it's never bit me. And I've put a lot of miles on several hard driven engines. Compression is as good as it was 75,000 miles ago... so why bother? Save some oil. Save some hassle. Save some money.

These people who change their oil ever 1000 or 2000 miles amaze me!

[crazypj]

Raul, you've started a discussion that has been on my mind for awhile also.

So, I'm going to add a little more controversy: Consider the opinion of the Shell Oil exec who claims oil changes are not necessary - merely topping up the oil can suffice to extend usage.

What that means; is getting every last drop out before adding the next batch is wholly unnecessary - making preheating even further unnecessary.

Since oil changes have become somewhat of a "religion" in maintenance schedules (and there is an oil-change ritual that goes with it) , this convention is all the harder to give up.

 That works fine on a plain bearing engine where oil doesn't have to lubricate transmission gears.
The shearing action breaks the oil which 'wears out' so periodic changes are necessary.
 Changing the oil every 1000 miles or so is just a waste of time and resources in my opinion
PJ

[kghost]

Lets consider why we change the oil....

After a while the oil becomes contaminated with cumbustion byproducts, moisture, and loses its viscosity.

Also as previously stated the gears "chop" up the oil.

To specifically answer your question......

Warming the oil to operating temp. suspends particles that will have settled and vaporizes moisture.

That way it all comes out when you drain it. Its not so much getting all the oil out...its getting the crap the oil suspends out.

Not talking big chunks....thats what the filter is for. Talking about the wee stuff the filter doesn't catch and the oil holds in suspension.

[Raul CB750K1]

Lets consider why we change the oil....

After a while the oil becomes contaminated with cumbustion byproducts, moisture, and loses its viscosity.

Also as previously stated the gears "chop" up the oil.

To specifically answer your question......

Warming the oil to operating temp. suspends particles that will have settled and vaporizes moisture.

That way it all comes out when you drain it. Its not so much getting all the oil out...its getting the crap the oil suspends out.

Not talking big chunks....thats what the filter is for. Talking about the wee stuff the filter doesn't catch and the oil holds in suspension.

That's exactly what I meant about "conventional wisdom". We all have read about contaminated and "broken" oil. We all have accepted that unleaded fuel damages the valve seats. The experts say it - it must be true. But do we have all the data? Or just the data provided by the expert with vested interest?

I'm not anal -I always feel uneasy when using that word- at oil changes. In fact, this last one I talked about was 200 miles after the period "expired". I'm not religious at oil changes, if oil change is due but I need the bike I will ride it as long as the level is correct. I have always thought that "old" oil is much better than no oil at all. People say "change the oil after winterizing your bike". I changed the oil that had been sitting for 15 years in my CB750 and it didn't look any more different than the oil that I just changed in my modern bike.


This is the first time I read about an Shell executive claiming that oil changes are unnecesary, but I have thought about it for some time. Today, 40 miles after the oil was changed, it looks black from outside the inspection window, and I bet I wouldn't be able to tell this oil from the one it replaced yesterday. If I had a bike I didn't care about I would not mind to do the test and never change the oil, just top off, and see how long it lasts. I don't think any bike manufacturer will sell a bike claiming oil changes are unnecesary - service is the bread-and-butter of the mechanics shops.


This was not intended to be an oil debate but a "conventional wisdom" debate. Why do we do what we do? Because it is what has been always done? Or because we know is the right thing to do?

[mystic_1]

Warming the oil to operating temp. suspends particles that will have settled and vaporizes moisture.

Exactly.

Running your engine before an oil change is like shaking up the orange juice before pouring, it stirs up the particles so that they're evenly suspended, so that when you pour it comes out evenly.  If you don't shake the carton, than the last glass to be poured is almost all pulp.  Same idea.

For a demonstration, take a medium amount of used oil and put it in a glass container.  Let it sit for a long time, eventually the heavier stuff sinks to the bottom.  Now, pour from the container, the thinner portions pour off first, leaving the heaviest stuff behind in the last few drops.


mystic_1

[goon 1492]

well said Raul, stuff like conventional wisdom and run some peoples lives, especially superstitious ones, I do believe in things like oxidation which it will do even setting over time, and fuel contamination, we all can tell I know i like to get a little oil on my finger and smell it when i am changing you can smell the gas in it, also on the new oil being black it will do that the first time it gets hot, and for the "chopping of the oil" I think thats more of a wise tale there.  I say that because if that were true by the time it got thru the refinery and completed processing it would be all chopped up and no good for us consumers  , 

[kghost]

Oil does burn ya know.....

When it does it turns to carbon.

Hence the oil turns black from carbon. (also the moisture and acids produced by combustion contribute)

Btw TwoTired had a good post awhile back on phosphorus and other metallic additives.

Phosphorus is the key component for valve train protection in an engine, and 1600ppm (parts per million) used to be the standard for phosphorus in engine oil. In 1996 that was dropped to 800ppm and then more recently to 400ppm - a quarter of the original spec. Valvetrains and their components are not especially cheap to replace and this drop in phosphorus content has been a problem for many engines. So why was the level dropped? Money. Next to lead, it's the second most destructive substance to shove through a catalytic converter. The US government mandated a 150,000 mile liftime on catalytic converters and the quickest way to do that was to drop phosphorous levels and bugger the valvetrain problem.

The oil does get sheared thru the transmission....not so much by the pistons.

[TwoTired]

I pick Wessner's approach.  Tim and Mystic's reasoning.

As for "chopping the oil".  The damage is primarily done to the additive long chain molecules that are used to make the oil behave as multi-vis.   The transmission will eventually turn a 10W-40 oil, into a 10W oil.  Still better than no oil.  But, there is less film strength at high temp and pressure between wearing metals.

The "turning black right away" is due to the heat changing it's photo-reflective properties, not it's lubricative properties.  So, you can't simply use color to determine oil change.  If the oil is still translucent dark/black, it's not condemned.  If it is murky opaque dark, it is, due to suspended particulates.  (filter can't remove them all, only the bigger ones.)

Or, so I believe.

[kghost]

Why change the oil?

Because the oil accumulates contaminates and breaks down with use.

Contaminates:

Abrasives -Air cleaners and vent systems only do so much. dust, dirt and other small particles will get in your engine and contaminate the oil. Air filters remove the big pieces but will never catch everything.

Metal particles - some wear is normal. So you have aluminium, steel, bronze and other metal bits floating around in your oil.  Oil filters remove the big pieces but will never remove all of them.

Water - a byproduct of combustion. When engine temps are high most of the water goes out the exhaust. At low temps condensation forms inside the engine. Think cold glass on a hot day. Every gallon of fuel produces 1/2 gallon of moisture.

Acids - derivatives of nitric and sulfuric formed by combustion. These condense in the engine and oil.

Carbon - also a byproduct of combustion. As is soot.

All these things remain in suspension in your oil.

Hot is better at containing these things in suspension.  

Where do you think the particles go when the oil stops circulating?

Ever pull an Oil pan?

Where does that black stuff come from?

Hot circulated changes are better than cold uncirculated.

Its not a myth, legend or tradition.

[Tower]

This all sounds reasonable, but Raul's point was just that: By sounding reasonable we can be convinced of the mythos without any real empirical evidence.

e.g. acid byproducts in oil.  Have you heard of sulphuric or phosphoric acids dissolving in oil?  Perhaps in water, but definitely not in oil.  And if present, when mixing oil and water and placing into a metal container - doesn't oil displace water every single time?

e.g. suspended carbon/soot.  Isn't that a lubricant also? Indeed one of the oil companies actually tried to sell such a graphite oil mixture at one time.

[kghost]

This all sounds reasonable, but Raul's point was just that: By sounding reasonable we can be convinced of the mythos without any real empirical evidence.

e.g. acid byproducts in oil.  Have you heard of sulphuric or phosphoric acids dissolving in oil?  Perhaps in water, but definitely not in oil.  And if present, when mixing oil and water and placing into a metal container - doesn't oil displace water every single time?

e.g. suspended carbon/soot.  Isn't that a lubricant also? Indeed one of the oil companies actually tried to sell such a graphite oil mixture at one time.

Shake a bottle of oil and water.

Hell shake a bottle of acid and oil.

The point as I'm sure you'll see is to SUSPEND the contaminates before you drain the oil.

Otherwise like you point out...its separated.

Its not conventional wisdon its physical science.

[Tower]

Yes, if we were talking about salad dressing.  But engine oil and water? At operating temp there is only water vapour and engine oil, likewise the oil always displaces the acid water on metal surfaces, regardless of the suspension's homogeneity - However, my point was that unless we have empirical evidence we are both speculating here,  probably speculation that favours the oil industry and not necessarily the engine.

If you are referring to "oil sludge" there are other factors and explanations to consider, I believe.

[Raul CB750K1]

I don't get the "carbon in the oil". If oil goes past the piston rings or valve seals, oil is burnt. It is not the gas that goes past the rings; it is the oil that goes past the rings. The force of the explosion forces the piston downwards, and the piston creates pressure in the crankcase. Does really exhaust gases go to the crankcases? Or the smoke is just from the hot oil smouldering?




Back to the oil, it is true that heavy particles sediment in the oil sump. Would the oil warming help in getting rid of them? I don't think so. The oil pan in my CB350 was full of sludge. But the oil pump is far away from it. No warming will make that sludge go to the oil pump. I get the "orange juice" example, but unless you lift your bike and vigorously shake it up and down, left and right, like a juice bottle, no oil circulation will help you dissolve the sludge in the bottom of the oil sump. Like if you drink the juice with a straw that only goes halfway in the bottle. No matter what the juice temperature is, if you stir the juice you will only stir and heat the upper layers, not the lower sediments.


Specially when there is some kind of "labyrinth" for the oil to help keep the oil level whatever the vehicle tilt is. Oil doesn't flow smoothly, it goes around a labyrinth, speed is reduced and the sediments will stay there for decades, whatever the oil temperature is.

More "conventional wisdom": What about bird#$%* in the paint? Is it really that corrosive? Has somebody first-hand experience of faded paint due to bird #$%*? Swallows #$%* in my air conditioner external unit, the guano stays there for months and gets cleaned with the rain and I haven't noticed any difference in the paint. And we are talking a single layer of paint in an air conditioner, not the candy + colour`+ lacquer. Is the bird#$%* a myth of the conventional wisdom or there is truth in it? What's the difference between bird and human "residues"? Why should the bird residue be more corrosive than any other animal's?


Another example of "conventional wisdom". How many of you cut the plastic rings that keeps the six-packs together? You are very environment-conscious so you are avoiding some poor fish getting caught in this improvised net. Now think for a second where your garbage go. Do you think for a second that the garbage truck dumps your garbage to the ocean? It gets separated in its very first stage -we in Spain have different containers for plastics, paper, glass etc. And each type of residue goes to a different recycling plant. Irrespective of the plastic rings being cut or not, it will be recycled and will only see fish if it gets the form of a inflatable raft.