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Keep topping off, I'd like to see what happens

 

Old oil will lose its properties which is the reason that it needs to be changed.

Spoiler: Example

Let’s say you add the quart three times in the interval and oil volume is three quarts.
After first add at 4t miles: 1/3 new oil, 2/3 old oil.
After second add at 8t miles: 1/3 new oil, 2/9 4t miles oil, 4/9 old oil.
After third add at 12t miles: 1/3 new oil, 2/9 4t miles oil, 4/27 8t miles oil, 8/27 old oil.
After forth add at 16t miles: 1/3 new oil, 2/9 4t miles oil, 4/27 8t miles oil, 8/81 12t miles oil, 16/81 old oil.

Even after six adds at 24t miles you still have almost 10% original oil left. And there are other reasons to do the oil change as well.

 

GEN II OCI is 5,000 miles....minimum. I find odd how people spend so much time trying to avoid doing such a simple, yet most important task to maintain their vehicles.

 

...or cheap out on a (for me, as least) twice a year evolution.

 

doesn't debris collect in the sump and get recirculated?

 

The reason the ocean is salty is it is never drained just topped up. Draining the oil gets rid of suspended metals that cause wear.

 

Let's put it this way.
Your operational theory is interesting. BUT...

People invest thousands of dollars into their automobiles in purchase.
They depend on them for life's luxuries and necessities, fun and work.

I've never understood the idea of going cheap or economical on Oil Changes.
Just changing the Oil and Filter as per recommended is NOT a huge expense, any way you cut it.

Therefore, I'm not going with a "Let It Burn Off-Top it Off" perpetual approach.

 

I really believe you could keep topping it up with Mobil 1. There was an extended oil change test years ago on a Camaro and they drained 1/2 cup every 3k miles and sent to Blackstone labs. The 1/2 cup was an issue since they added back new each time and thus the oil and additives were refreshed. I'm fully sure a full quart of great oil added would make oil test good again. Heck changing the filter will make it great.


iPhone ?

 

What are you driving? Prius? What year? How many miles? Nothing in your signature, or info. Assuming second gen since you've posted here.

If oil consumption is high enough then yeah, you're practically doing an ongoing oil change. But considering second gen oil change interval: 5000 miles or 6 months, you're not there yet. And if you're under there changing the filter, might as well drain the oil too.

 

If it’s the same test that I found online they “only” did 25t mile test.

If OPs car consumes 1/3 of its oil capacity in 4t miles and he fills it to top mark only when level reaches bottom mark there still is (2/3)^6=0.08779 or about 9% left and more than that if OP tops the oil up before its one quart down (which should be done).

So “test” that OP is suggesting is harder on the engine than test that Mobil 1 performed.

 

I'm not a good reference but was stating my view. I change the oil in my 2005 Prius somewhere between 10k and 15k miles. Depends since my household has 5 vehicles and I try to do as many at once as I can. My Prius has just turned 180k miles. Runs great but uses a qt every 3k to 4K miles. I always use synthetic oil (mostly Mobil 1 but Some Pennzoil) with Mobil 1 or Bosch filter. Basically between changes the Prius gets at least 2 quarts of new synthetic oil added topping up the additives. I'm very comfortable with that.

The study I was referencing is very old. It was from the days when synthetic was rarer.

Mobil 1 Test Results

Anyway it's all up to the users comfort level. I personally don't want anyone messing with my vehicles to much. Changing every 3k miles is a lot of opportunity to misthread a drain plug or screw up a filter.






iPhone ?

 

I'm not 100% sure of accuracy but the Key points from the study:

-Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it.
-Topping up the crankcase is a critical component of extended oil change intervals, and frequent filter changes are most likely the key to extreme-length intervals. The cumulative effect of even minor top-ups, let alone a filter change, substantially increases the longevity of the oil.


I do agree with the issue of changing too often. Filters filter better up until they clog or restrict flow too much. Dirt held back makes the filtration better since pores are smaller.



iPhone ?

 

Sadist

 

That's what it says alright, but how can that be? I'll stick to the Canadian schedule anyway, 8000 km or 6 months. And it's invariably 6 months that governs for us.

Nearing 60,000 km and a bit past 5 years, zero oil consumption between changes. That's eerie for me, never had a car before that didn't consume a little.

I wouldn't say the zero oil consumption is necessarily due to frequent oil changes, maybe just lucky: got one with tolerances just right? And who knows, down the road.

 

Go with it then...it's your money not mine. This mechanic will keep taking proper care of his vehicles.

 

Topped up with fresh water, rain

 

oil change debates go on and on. I wouldn't mind have the result/data on this experiment.......

 

Why even use oil? One jug of Prolong will protect for life!

 

i think the fact that toyota has different oil change intervals in different countries tells us everything we need to know.