No, it's fine. Meanwhile I had a look in the workshopmanual, and that 'old' D16Z5 engine needs 10W40 in API SE or SF. Have a look at this, official API site: API | Oil Categories So the best I can do is take an oil that comes as close as possible to that SF specification (so not to high in API rating!). And I found out this (shops are close to my door): the cheapest homebranded oil from a DIY shop is still 'to good' in API rating for that old engine (APS SL). https://www.gamma.be/nl/assortiment/gamma-motorolie-10w40-semi-synthetisch-4-l/p/B592307 Going higher in grades only increases the risks of problems. I think in the first place to all the old rubbers and gaskets. But thanks for the help!