Change from semi synthetic to full synthetic.

[WhackySpark]

Well you probably guessed my question.I've always used semi synthetic 10w40 in my 2003 1.9 diesel but i was gifted about 10 liters of full synthetic from a friend.

I've read a lot on the internet and for the moment a lot of what i read contradicts each other. I want to know if it is ok to do an oil change and switch from semi to full synthetic.

Any advice would be appreciated.

[cancunia]

AFAIK it should be ok, so long as it has the same viscosity. Thinner oil will not coat the bearing surfaces as much as thicker oil and may lead to wear due to bigger gaps between moving parts. I've read in some places that brand new engines are best run on semi synth for a while as they need a small amount of friction to allow parts to bed in.

[Islander71]

I had some C3 5w30 fully synthetic oil left over from previous car, and after advice on here used it. It seems to be fine 4,500 miles later.