Hitchcocks Forum

Everywhere I look I get widely differing opinions on this question. I suppose it'll be the same here but here goes.
Almost every engine manual I have ever read states you should change the engine oil every year regardless of mileage.
Why should I do this? Does the oil go off?
I appreciate that the oil will absorb a certain amount of water, but surely this will be driven off when the oil gets up to temperature.
My wife's Honda CBF250 (and my second mount) only does about 1500mls a year and I am loth to chuck away what seems to me like perfectly good clean oil by changing it after this small mileage.
Actually it's two years since I last changed it, but that is still only half of the standard 6000ml normal change interval.
I can understand it with an Enfield as the oil gets mucky pretty quickly but the oil in the Honda still looks almost the same as when I poured it in.

Hi Pete

Blow by on the pistons causes oil contamination and over time this contamination will degrade the oil so the short answer is, yes you need to change it even if it looks clean.

Hi PETE,--------- get yer hot coa-coa, curl up on the settee and have a read of this }---- http://www.machinerylubrication.com/Rea ... -stability -------------------------

Strange how the oil that comes up from under the ground, millions of years old, is still in excellent condition.

Good subject!
I think a huge amount of oil is wasted changing oil as often as many do.
An average for cars is around 15000 - 17000 miles!

On the other hand - highly stressed engines with smaller quanities of oil certainly need fairly low mileage changes to prolong engine life.

I'm sure I've read somewhere that even brand new oil in an unopened container has a 'shelf life.'

Certainly, used oil (even if used for a low mileage) degrades due to the products of combustion and condensation. It can even be harmful to bearings etc when left in the engine when it is left standing for long periods.

Hi guys--------------- which is why I've always suggested that you change your oil and filter before laying-up for the winter, rather than at the start of a new season..LEON, that "old" oil has never been in the presence of oxygen although the "Shelf life" idea I suspect is more to do with trading regulations, legality etc. rather than actual degrading of the oil within the can....GUYS, don't forget to re-cycle that old sump oil either at your council re-claim site OR }---- donate it to your local preserved steam railway where it is used to lubricate points, rollers, rodding etc....every little helps !! ( where've I heard that before ??)

Thanks Alan, interesting article. I hadn't thought of oxidation. Also the Honda only takes a litre and a half so I shall change it as directed.
On the other hand my car engine says it's OK for 18,000mls between changes! No way I'm doing that whatever the boffins say. 10,000 is plenty.

I think there is a tendency for car manufacturers to stretch the service intervals beyond that which is ideal, in an effort to attract fleet buyers with whom maintenance costs have to be minimal. After 3 or 4 years the fleets get shot of the cars leaving the second hand owners to pick up the bills of neglected maintenance!

AlanR: I don`t know about that, Fred Flintstone`s car ran alright on it.