mixing oil when topping up

The message from "Yaz" contains these words:

No.

My experience is different. My old Fiesta van (W reg, 1.8TDi) had 5W/30 oil in it, and I topped it up with 10W40 (all I could get hold of at the time) and between then and the next oil change it kept on requiring regular top-ups (can't remember exactly how much and how often, but definitely out of the ordinary). After I'd done an oil change with 5W30 (i.e. that was the only grade that it had in it) it didn't need topping up since, and never used any oil (or certainly not any noticeable amount) in the time I had it.

Peter

I would not have thought there is significant risk but it is not good practice.

What car/age is it?

A modern engine needs a decent semi-synthetic so putting the cheaper stuff in (even if not mixed) is not a good idea.

"Alan" wrote

It is a Mazda 323F 1.5 / 1997

If you go for the same grade (10w50) then there shouldn't be any problems. Have a look in the book and see what it's supposed to have.

Rumour has it that you're not supposed to mix mineral and synthetic (what's semi synth then?). If you're worried drain it and refill with the proper stuff. Mixing different mineral oils or synths is unlikely to cause a problem though

-- Malc

A car 'needs' what the manufacturer recommends as a minimum. This is still commonly a mineral oil. If in doubt, RTFM.

Huw