10W30 or 10W40 oil for my gen 3?

[TeaMonsta]

Downloaded a data sheet for my Surf which tells me that the car takes either 10W30 or 10W40 engine oil. What's the difference? (I'm sure I read a thread on this recently but can't find it).

[muddle]

10w40 summer and 10w30 winter. I just use 10w40 all year

[TeaMonsta]

Thanks Muddle. How often should I be changing the oil? I think I read somewhere that it should be every 3000 miles for a Surf, in which case I'll run 40 for summer and 30 for winter as my annual mileage should be about 5000 - 6000 miles.

[muddle]

Every 5000 kms or 3000 miles.

[TeaMonsta]

I did read that right, then! Glad I checked. Thanks for your help. Might as well run the two oils for the different seasons, then. Recent winters up here in sunny Aberdeenshire have seen the temperatures get down to minus 20. And I bought the car to get us through the snow as the farmer doesn't come round until midday to clear the road round these parts.