Synthetic oil, change interval

[NickCLotus]

Just wondering your opinions on how long to use fully synthetic engine oil before changing it?

Currently at 7k miles since last change and two years: not exactly golden coloured any more but only a little bit black.

[andburg]

i think the general rule is to look at your service schedule. Every year at maximum the mileage set out in the schedule, the more you change it the longer the engine internals should last.

[HJG]

Rule of thumb nowadays is to halve the manufacturer's recommendation.

[stevieturbo]

NickCLotus said:

Just wondering your opinions on how long to use fully synthetic engine oil before changing it?

Currently at 7k miles since last change and two years: not exactly golden coloured any more but only a little bit black.

What car ? what usage ?

[NickCLotus]

TU5JP4 engine in a Peugeot, average mixed usage.

[Sheepshanks]

I don’t believe in over-servicing but two year old oil in a lightly used car isn’t something I’d be comfortable with. Oil that doesn’t regularly get properly hot gets condensation in it and it turns acidic.

[_Rodders_]

Everyone will do things differently, there's no hard and fast rule beyond very generally speaking the more often the better.

I do mine every 5k or yearly whichever comes first.

[Pica-Pica]

I stick with BMW service intervals, have done for the last 29 years.

[Super Sonic]

Pica-Pica said:

I stick with BMW service intervals, have done for the last 29 years.

Worst ''I drive a BMW, not a stting Peugeot" post ever?

[itcaptainslow]

Only conclusive scientific means of deciding is to get an oil analysis done of the oil that's in the engine...which while possible, is a tad impractical. Far easier just to change it

The Peugeot interval was 2 years/20k miles, whichever comes first IIRC on that engine, which feels rather...long. As the poster above alluded, entirely possible for low mileage oil to become acidic.

For the cost of some oil and a filter, it's advisable just to change it. Cheaper than an engine, anyway!

[ARH]

I service my cars every easter, its far better than going out and mixing with the crowds, I have done this since the early 80's whatever the car. Most of my cars cover between 4 and 10k miles a years. Right now 2 of the cars I have cover about 7k miles a years. The other only does about 2k miles.

I too would not be happy to leave oil in a car for over a year. Especially with low miles covered, but then if you cover high miles it will need doing every year or more anyway. At most I would probably be around the 12k miles mark for an oil change. Oil is a lot cheaper than an engine, even if you buy "top quality" branded stuff.