Mixing oil ?

[Nick Turley]

Oil is cheap why not change it ?
Regular changing makes the engine last a lot longer.

[David Stepney]

I change mine every 2500 miles. This was based on the recommendation for early VW Beetles with just a gauze filter of 3000 between oil changes, although I accept that air cooled engines are rather harder on their oil than water cooled ones. I use a good quality semi-synthetic 10/40. Not had any problems so far touch wood. Incidentally, my car’s handbook suggests that the engine oil should be changed ‘occasionally’ (whatever that means).

[Chris KC]

Over 2500 miles of driving I would put in about 6 litres (i.e. at least twice the capacity of the sump) of fresh oil anyway... I only drain and re-fill when I take the sump off (n.b. I use a full-flow filter).

When touring I might start off with Halfords, Duckhams or Morris but when that runs low I use any 20W50 I can get - my current collection includes 'Classic' from Biltema in Sweden and 'Wolf' V-Twin oil from Germany... It all mixes quite happily and I've never yet lost a bearing to poor lubrication.

[David Stepney]

My car uses about a pint every 500 miles or so, so very little of the initial fill is left by the time comes for an oil change. What changing the oil does is to remove all the accumulated crud that inevitably builds up inside.

[Colin Morgan]

If you add back a pint back every 500 miles, or half a pint every 250 miles, then there is about 1/4 of the original oil still in there after 2500 miles.

At that point - after 2500 miles - the average miles seen by the oil in the sump is around 1000.