My Volvo 340 is a 1988 model, 4 speed 1.4 with 97'000 on the odometer. I want do do an oil change but which is the best oil to use? I usually use 10w40...

I stick Castrol GTX in it, Halfords have stopped selling it in 10W40, but 15W40 is fine to use. Any mineral or part synthetic oil will be OK with a B14, just change it regularly and remember you generally get what you pay for (but don't need or want expensive fully synthetic modern oils).

Is 10w40 ok though?

Yes 10W40 is what is specified for it I think.

Saw today my local Tesco now has Castrol GTX in 2 litre bottles for £6.49 in both 10W40 and 15W40 grades, a bargain!

Ideal, Im off to Tescos to get some 10w40

Not sure if they're still doing it but ASDA was selling Castrol GTX 15W40 4l for £10.

This was a couple of months ago now though, needless to say I have a couple sat in the garage

I got x2 2 litre bottles of Castrol GTX 10W40 for nearly £13 in Tescos, what a difference to the running smoothness of my car...

My theory: regular changes are more important than the quality of the oil. Forget synthetic nonsense which hadn't even been invented when the car was in production, 10W 40 is good for serious subzero winter temperatures, but 15w 40 will do you proud as well.

And don't forget the oil filter, the best ones have a kind of valve in them, that stops the oil draining out when the engine is turned off. Volvo OEM, Bosch, and others have these, Halfords' own and Mahle do not ...

Cheers

Tom

My Haynes manual specifies that I should use either 10W/30 or 15W/40 oil for a B14 engine...