Changing oil vs.filling oil

I wonder whether I should change oil every 3 months (or whatever), or whether I can sometimes just fill it with fresh oil.

If I can, should it just be a temporary or rare thing, or how often can I just fill oil?


You should change oil according the the maintenance schedule that came with the vehicle, lawn mower, or whatever it is you’re changing oil on.

You should add oil any time the level drops below full on the dipstick.

Adding oil (if necessary) does not eliminate the need for periodic oil changes.

It is a Honda Civic.

I agree, you should always change the oil on schedule. Just filling it doesn’t remove contaminants or leave you with a fresh clean oil filter.

You only add when it’s low. If you change your oil when schedule then it should NEVER get low enough to add (at least that’s the theory).

OH! That’s the “new feature” hidden away there below the post.

I’m confused by your question. What do you mean about “just filling” it? How low is the oil at that point?

If he doesn’t change his oil properly…it’ll be real low after a few k miles because the cylinder walls will be scared and there will be oil blow-by.

The folks at Car Talk plaza seem to have employed the services of a web programmer, but not a web designer. Programmers usually make lousy designers.

Think of it as a glass of beer.  If it runs dry in 10 minutes, you refill it, if it looses it's taste in 10 hours, you replace it.  Same with oil.

I know if I were a cylinder wall and nobody changed the oil I’d be scared…

Reminds me of a friend with the older blazers from the 70s. It was burning oil and in each 5KM of driving would go through the same amount of oil top offs that the capacity was. So his logic was that his oil gets changed every 5 KM and did not change oil. After 30KM the engine stopped running. We opened it and it was seized with this black tarry material.

HA-HA…I missed that one…SCARRED.

We opened it and it was seized with this black tarry material.

It’s called sludge. And that’s what happens when the oil and filter are NOT changed.

“So his logic was that his oil gets changed every 5 KM and did not change oil.”

Maybe what happens is the lowest viscosity fractions of the oil get selectively removed and burned, leaving the thicker stuff behind.

Good point circuitsmith; the heavy crud accumulates in the bottom of the crankcase, gets picked up by the oil pump and distributed through the engine, and finally blocks the oil pump intake, finishing off the engine.

Other experimenrts show that only topping up the oil, and never changing it will result in approximately 60,000 miles of engine life depending on how sludge-prone the design is.

Years ago there was a claim for 100,000 mile oil; all you had to do was change the filter every 1000 miles! On a normal car that would mean continually changing the oil. But there was still the crud in the crankcase, which would get carried over by the oil pump.