[Solved] Focus MK1 2001 1.6 Zetec: Best Oil for 200,000km City Driving, 5W30 or 10W40? No Leaks, CO Issues

Hello.
As in Title.
1.6 zetec focus 1 almost 200,000 km, a copy from Italy.
The car takes some oil. I drive 95% of the city. The car runs 20 km one way every 2 weeks, 100 km every six months / year.
Takes little oil. About 1 liter from replacement to replacement - 15,000 km. I travel a lot, but around the city. Gear change 2200-3500 thousand, depending on whether it is a hill or full.
The engine has no leaks.
The police once took evidence for not meeting the CO standard. It was a little bit out of the way, but not much.
The engine performs great. It smokes, drives, has a kick, screwed in, reacts stiffly to the gas pedal, does not go out, etc. It burns normally.

Now the question:


I run Ford 5w30 on oil, it was poured all the time.
Changing the parameters, or pouring such as a funnel and topping up, an average refill comes out every few months.
If you exchange it, which one?
The previous owner, a motoring enthusiast, said, God forbid, do not pour 10w40 in this engine, because it will shorten the life.
Mechanics, or pseudo-mechanics say:
- 10w40 hopper
- 5w40 hopper
- 10w30 hopper.

Each one is different. What now?
I ask people who know each other.
I am asking because I do not want to destroy the engine, but rather I want it for life. The sheet is great. A copy from Italy.

Hello, you pour the oil as ordered by the manufacturer, you do not change anything.
You have minimal oil consumption (many would be happy) - if you want the loss to be less noticeable, change the oil every 10,000 km.
Best regards.

Cool. Thank you... for the answer. So I will.
Another thing. What about the oil filter?
I change it when changing the oil. It comes out every 12 to 14 months.
Enough?
The second thing is whether to change the oil in the box?
Works very well, nothing to hang on to.
Until now, I used the rule - replacement every 50,000, or every 5 years. It makes sense?

There is no engine oil change without a filter is a complete set.
Changing the oil in the box will not hurt - after the change it will be fresh and you can check it from time to time and always add it.
Oil change, i.e. max 2 liters, is not a huge cost every 5 years, as you write. best regards

Thanks. I know that when changing the oil, always change the filter. Most think the filter is even more important. I'm just wondering if when driving around the city, not to change the filter more often. Once in 5-6 thousand ...

Without exaggeration. On our market, 5W30 probably all have a lot of synthetic, if not counterfeit - replace when you replace it, it's far from harmful longlife, unless these replacements are less frequent than every year, then shorten to a year, regardless of the mileage.
As for the oil intake - it is nothing and I would not be bothered.
The question is what to do if he ever grows? Apply "thick" but with the head. What does it mean?
Look for high-quality synthetics by increasing the high temperature index by one (i.e. for your 5W40), of course, to meet the quality standard.
Why not 10W40? Most in our market have much less synthetic additives than 5W30 or 5W40. In addition, 10W will make jelly faster in frost, ie in winter more difficult to start, accelerated wear, etc. No sense.
Why not 10W30? I don't know if European cars tolerate it, maybe American cars. It will get "sparse" like the current one after warming up and 10W is a waste of cold engine lubrication. Nonsense in our changing climate and I doubt it would be the norm for this engine.
Why not change from one time to the 5W50? Because if it has delicate rings, the oil film will be too thick and it will burn even more.
As for synthetics and minerals, I intentionally write more synthetic additives, not synthetics, because it is a bit more complicated and with some fractions even conventional (esters and polymers are synthetic and such oil is already chemically similar to soap, but the cracking product is a slightly improved component of oil oil, and on the Polish market it is probably not regulated how much it should contain to get a semi-synthetic or full synthetic patch). In any case, the finer the oil the better.
Also throwing numbers of the 10W40 type, omitting the base (mineral vs. Synthetic), the way of use (for burning rubber it is 5W50 or even 10W60 for longer events on the track), the manufacturer's standards or the fact that you almost do not take this oil, suggest a poor approach to this point.

Thank you all!
Helmud7543- Thank you. A great and comprehensive answer.
You can close the topic.

Thank you all!
Helmud7543- Thank you. A great and comprehensive answer.
You can close the topic.

Added after 56 [seconds]:

The problem was solved mainly by the last post - Helmud7543