Never change oil, only filter?

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JoeWeinstein

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Hi all. I know this smells funny, but tell me where.
If I have a car that has a 5-qt oil capacity, and
burns 1 qt/1000 miles, and I keep it topped off,
adding a 1/2 qt every 500 miles, I'm already essentially
changing the oil every 5000 miles, right? If I use a
high-enough quality oil for a 5000-mile change frequency
or better, am I covered as far as oil is concerned?
Joe
 
No, let's say I'm running the correct viscosity for my
motor... No one should run thicker, just to stop
consumption. That's like turning your blood to jelly,
to stop a hangnail from bleeding.
 
1/2 qt every 5,000 miles is only a fraction of your car's oil capacity. It won't replace an oil change.

Also, sometimes oil consumption produces acidic by-products, and that partly offsets the benefit of adding oil.
 
I'm adding 1 qt per 1000 miles (1/2 qt every 500)
so total replacement every 5000 miles. So my oil
is always about 2500 miles old, as a mix.
 
When you say it burns oil. You mean you have no leaks? So the oil loss is due to valve seal and worn rings?
 
Hi,
JoeWeinstein - Welcome to BITOG - I hope you find your Membership is a very rewarding experience

You ask a question that has been a real life experience for many Operators in the Trucking Industry for several years

WHAT FOLLOWS APPLIES ONLY TO DIESEL ENGINES

STARTS (my words)

There are devices that extracts a fixed amount of engine oil and blends it with the diesel's warm fuel. It is then consumed.
At the same time fresh filtered make up oil is supplied in a set regime. A supply tank must be fitted of course and this can be sized to suit. Both systems are "fail safe"!

Both supplies (old out/new in) can be based on time or distance! And the total oil change cycles can be set to either. Filters are replaced as the engine manufacturer recommends. Using a centrifuge cleaner could extend FF filter change out to well beyond 200k miles. Using SS FF filters too would extend to filter cleaning at around 200k miles

Operations are via an electronic control module which can vary total oil replacement according to sump capacity and UOA results

ENDS

A Client of mine has been using this system since 2001 in the very remote Gulf Region here in Australia. The systems are fitted to CAT, Series 60 Detroits and Cummins engines. These (up to) 600hp vehicles operate as Triple Road Trains (Fuel Tankers).

They operate over many very poor quality and dusty (and as of right now - flooded) roads. Reliability is a must. The Company is one of the oldest continuously operating Transport Companies in the World

They use Shell mineral 15W-40 HDEOs (for fleet standardisation) and operate on a strict maintenance programme. They do NOT have a conventional OC cycle of course

The only problems have been in calibration and the odd minor system component failure. Many millions of kms been covered since its introduction. Their maintenance system was initially installed by me

In the near future closed lubrication systems will be attached to both cars and trucks (initially). This will be a giant leap forward in energy conservation and pollution control!

So what you ask can be answered by saying yes - with a few reservations. The prime issue is to establish an all encompassing "management" system to ensure that excellent and consistent lubricant quality is maintained (UOAs are a great tool here) and that filtration is not compromised in any way
A cut off point OC interval wouyld need to be established in most cases too

Would I do it in my vehicles and in my circumstance? - probably not

I find this an interesting topic - thanks for starting it!
 
Last edited:
Originally Posted By: JoeWeinstein
I'm adding 1 qt per 1000 miles (1/2 qt every 500)
so total replacement every 5000 miles. So my oil
is always about 2500 miles old, as a mix.

Yikes, I'm sorry. I added a zero when I read your first post.

Definitely check for leaks. If you don't find any, there's a problem. Whatever is causing the consumption, as well as the likely by-products, would not be fully compensated for by the topping-off.
 
Originally Posted By: d00df00d


there's a problem. Whatever is causing the consumption, as well as the likely by-products, would not be fully compensated for by the topping-off.


Well said, My thoughts exactly!
 
If it were me, I'd do a leakdown test to see if I had blowby and an oil analysis. If it wasn't too bad then I'd consider your perpetual OCI.

the main concern would be combustion byproducts contaminating the oil and perpetually running oil in very poor condition. You would be continually refreshing the additives in the oil but it may not be enough.

How much do you like this car?
 
You will still get a build up of stuff in the bottom of oil pan. This stuff can interact with(ie contaminate it)oil. Unless you dump out oil this stuff will remain and actually accumulate. The more of it the more the oil will get contaminated, maybe even sludged, especially the oil screen on pickup. If unable to repair start using a HM version of the brand/visc that you are currently using, and see if that helps. If not next logical move is to up visc. Are the plugs getting fouled often? some ashless 2 cyl. oil in gas could help here, and may unstick rings if thats part of problem.
 
Changing the filter every 5000 miles will help make this idea work. It also depends if it's highway driving or lots of short trips and cold starts.
 
no, it doesn't work that way, because the oil u put in 4000 miles ago is still mainly there, and worn out. keep doing what you suggest and you're in for an engine rebuild, i would say, in about 30,000 miles, if you're lucky.
 
Originally Posted By: JoeWeinstein
No, let's say I'm running the correct viscosity for my
motor... No one should run thicker, just to stop
consumption. That's like turning your blood to jelly,
to stop a hangnail from bleeding.


I'm surprised my TL is still running with that Jelly going through it's veins.
smirk2.gif
 
Yes, let's assume that the oil lost is not leaked externally,
but burnt, due to some combination of ring, valve, and other
wear. Let us also assume that the oil consumption doesn't
cause any other problem, and the wear or tolerances that
allow the oil loss are not getting any worse.

For those that don't understand it, if such a car consumed
zero oil, and you changed the 5 qts every 5000 miles, you
would similarly be running with oil at an average age of
2500 miles, but for some time you would be running with
a whole crankcase of 4500-mile-old oil, whereas with the
car described originally in this post, the car never runs
with oil (as a whole) older than 2500 miles.

And to make it simpler, for a car that doesn't leak *or*
burn any noticeable amount of oil, it would be like draining
1/2 qt every 500 miles, and topping off with fresh. No
need to ever drain the sump, right?
 
Originally Posted By: BuickGN
Originally Posted By: JoeWeinstein
No, let's say I'm running the correct viscosity for my
motor... No one should run thicker, just to stop
consumption. That's like turning your blood to jelly,
to stop a hangnail from bleeding.


I'm surprised my TL is still running with that Jelly going through it's veins.
smirk2.gif



I am only saying that you should run the viscosity
recommended for your engine, and not put in any
thicker oil, just to stanch a symptom. If 20w50 is
right for your car, that is what you should run,
but if it was supposed to use 10w40, and now it's
older, somewhat tired etc, I don't think you want
to thicken your oil. It may stop consumption, or make
the valve train quieter etc, but I worry that it
will still cause extra wear, at startup when thin
oil is good, and also may not adequately lubricate
those parts of your motor that still have the original
gaps that require the thinner oil. For instance, in
trade for less oil past your worn rings, you may also
be getting less oil through your still-OK main bearings...
I wouldn't sacrifice or jeopardize my bottom-end for
any savings of a qt. per 1000 miles. I'd either get
my top-end rebuilt or live with it.
You don't want pressure, you want flow. Viscosity
is liquid friction, a necessary evil to be accepted
only as much as necessary. Formula 1 engines use very
thin oils, like straight 0-wt. Do what the manufacturer
says....

So, back to the original question; and it's sounding
like if the oil qualities are such that it's perfectly
adequate at 2500 miles of use (assuming the motor's
blow-by etc does not unusually dilute or use up the
oil's additives enough to defeat the oil's normal
recommended life) it sounds like the idea is not wrong.

Joe
 
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