Modern Oil quality and servicing schedule

[Nimrod]

67 traveller. the original service schedule says change engine oil every 6k miles or 6 months.
With the quality of modern oils compared to oils 40 years ago, is that now strictly necessary? (I did less than 3k miles in the last year....)

[Axolotl]

If you are using the correct 20W/50 oil, then it is "new", not "modern", in the sense that its formulation is probably not much different from what it was when the service interval was specified.

Also, you are using it in an "old" engine, with much coarser design tolerances and simpler materials than a modern engine, so you are likely to get more oil pollutants from combustion gases, unburnt petrol and metal wear than a modern oil has to deal with.

The change interval should be more frequent than for a "modern" oil in a modern engine. (Try fitting a magnetic sump plug if you want to frighten yourself next time you change the oil. Observe the pile of tiny metal slivers it attracts).

I'd say, stick to the recommended intervals, but use a bit of common sense. There's no need to change it if you haven't driven the car.

My opinion would be that once a year is probably enough if you're only doing 3k miles in that time.

[Willie]

Yes, if you only do that low mileage I would change the oil once a year and the filter once each two years (6000 miles). The oil is cheap enough and,obviously, is the single most important item for ensuring a long engine life.

[bmcecosse]

Aye - once a year whether it needs it or not! Probably best to change it just before the winter lay-off period if you have one. If you use the car all year round - then change it now (Spring) to sweep out any moisture that will have gathered during the relatively cold running during the winter.

[salty_monk]

Fred is running clean oil through a dirty filter really ok? I only ask because a lot of the motorbike guys over here seem to do that & I was always of the impression that both should be changed together.....

Common sense tells me that a filter won't clog in 3k miles though but there must be some small particles & dirt attached to it that flush back into the oil... (I suppose the same could be said for the whole engine...)

Dan

[rayofleamington]

changing the oil once a year at 3K and the filter every 2 years / 6k is going to be better than changing both every 2 years / 6K

The chances of a filter getting blocked before 6000 miles if the engine is well maintained and the oil changed regularly is very low. It's normally recommended to change both together but that's based on going for a long service interval if you reduce the service interval, it's not mandatory.
A partially blocked fillter will create more back pressure - the increased pressure then reduces the performance of the filter (bigger particles get forced through) and in extreme cases the restriction can starve the engine of oil! On the flip side, if the filter isn't choked then it still works as intended.

[Willie]

Dan, yes, in my opinion anyway, the filter will handle six thousand miles with no problems. So would the oil actually but it still deteriorates over time as well as with mileage so I would always change it once a year
regardless. I like your new address!.