Oil change intervals on new vehicles

[bobc455]

Not so much loss of lubricity, but it gets hydrocarbons mixed in (as well as moisture and other acidic things).

I use an extra-large filter, larger than the recommended one, so I have plenty of filter surface area.

Filters only take so much out of the oil. The most lubricious oil in the world still gets dirty.

In the "old days" it was common to change the filter every 3rd oil change.

If you want to know how your filter life is, cut open your filter (i.e. a hacksaw) after you have changed your oil and see how the element is holding up.

-BC

[Draigflag]

No need here, even high performance high compression engines like mine have 12,000 mile intervals now, but our fuel is also considered sulphur free.

Note: the injectors force fuel at 200 PSI into the engine on mine, strong enough to cut solid concrete!

[fenixguy]

Change it early or run it the full recommended interval. Your engine will never know the difference.

Just to add some more confusion to the mix, Honda recommends changing the filter every two oil changes. And in the case of my Civic, that would be a filter change every 20,000 miles if going by the manual.

[R.I.D.E.]

Originally Posted by Draigflag

No need here, even high performance high compression engines like mine have 12,000 mile intervals now, but our fuel is also considered sulphur free.

Note: the injectors force fuel at 200 PSI into the engine on mine, strong enough to cut solid concrete!

200psi? maybe 200 atmospheres, about 30,000 psi.

[Draigflag]

Originally Posted by R.I.D.E.

200psi? maybe 200 atmospheres, about 30,000 psi.

Oops, 200 bar is what I actually meant lol, about 3000 PSI.

[R.I.D.E.]

Here you go, as high as 44,000 psi. Multiple "mini" injections while the combustion event is in progress, eliminating the "diesel knock" by extending the combustion peak pressure. WE are getting very close to a practical Homogenous Charge Compression Ignition (HCCI) in gasoline engines, possibly using a mix of different fuel types.

https://en.wikipedia.org/wiki/Common_rail

[Draigflag]

Mine is a gasoline engine, but it does sound diesel like on tickover, would that be due to the high compression perhaps, similar characteristics to a diesel?

[R.I.D.E.]

The predictions are that HCCI will increase efficiency by 25%. I would imagine your Renault is direct injected which does create some diesel like sounds and allows higher compression. I think the Mazda sky-active gas engine has 12.5 to 1 compression and uses high levels of EGR and knock sensing to control any potential preignition. True HCCI in a gasoline engine has the mixture virtually perfectly (aka homogenous)distributed when the ignition occurs without any spark, like a diesel.

Some engines these days actually have the throttle plate wide open even at lower throttle positions and loads, using valve timing, EGR, and fuel delivery amount to control power output.

[trollbait]

The next Mazda3 will have an HCCI engine.

[cuts_off_prius]

This may be of some insight. I've been looking at a long-term ownership maintenance guide lately for BMWs written by an expert from Roundel and Bimmer magazine. Basically, when the 4 year/50,000 mile free maintenance program kicked was introduced around 2004, BMW lengthened all of the maintenance intervals, despite there being no changes in many aspects (like fluids). The only change seemed to be who paid for the maintenance. For example, before maintenance was "free," the mileage for break-in oil and filter change plus differential oil for new cars (mine is used) was 1,200 miles. Oil analysis showed that engine and driveline oils in new BMWs were full of metal by then. Also, BMW has an oil and filter change interval of 15,000 miles for their modern cars with synthetic oil. Using BMWs recommended Castrol oil, the expert who wrote the guide says oil analysis shows that changing every 5,000 to 7,500 miles is "prudent for long-term ownership." For the ATF, the interval was even "lifetime" meaning you never change it. BMW then revised it later to 100,000 miles. The expert recommends 60,000 miles ATF at the latest for long-term ownership.