I would normally recommend doing dealer servicing at the recommended intervals in order to preserve the conditions of your warranty - just in case something "expensive" fails and you need to rely on it. You say the car is an 18 plate and you're only now going to get it's first service done? I know covid has disrupted many things, and yours is only coming up on the 9,000 mile mark, but oils etc degrade with age as well as mileage so, personally, I would have submitted it before now following the time related service recommendation? Of course, assuming you had the standard warranty (3 years) that will now have expired so preserving warrant rights is now irrelevant - just saying this for the benefit of others.
Sounds like you're going to do this service yourself? I used to be very keen on buying genuine parts and when I worked in the trade I had easy local access to local dealers at trade prices. However I would also, from time to time, buy generic parts (but OE Quality and I only buy brands I "know") from local motor factors when perhaps something had to be put on back order with no definite delivery date. Been doing this for years and on reflection I realized that I've experienced really no difference in reliability whether the parts were genuine manufacturer branded or OE quality after market parts. Nowadays I rarely buy genuine parts but do take great care to buy quality brands - Sachs, Gates, GKN, Bosch, etc you get the idea - and I buy from trusted sources to minimize the possibility of counterfeit parts. I think it very likely that the brands I buy are also supplying the manufacturers.
So who do I buy from? For the Fiats it's either Shop4parts:
https://www.shop4parts.co.uk/ or my local trade Factor (SRS)
https://allianceautomotive.co.uk/member/24736/srs-autoparts-edinburgh/ if it's small stuff like filters, wiper blades etc. If I've a bigger order going in to S4p then I'll get service parts at the same time but if I'm only doing an oil change or similar, maybe replacing a track rod end, I'll just go to SRS. I'm very fussy about my oil, only use vehicle specific products and have run all the cars on Fuchs for some years which I buy online, often from either Powerenhancer:
https://www.powerenhancer.co.uk/ or Opie Oils:
https://www.opieoils.co.uk/ I do this because with oil you need to be careful about special offers because you might end up with old stock - most containers are now date stamped and I think the oil companies say you can consider an unopened container as new until it's 5 years old? However I've never had either of these two supply stuff that's more than a few months from date of manufacture. By the way, both are very helpful and will freely give advice on the phone if you're unsure about anything. Worth searching for the oil you want on ebay too as both of these suppliers sometimes run special offers which can save you a bit over even the price they are showing on their websites. I also like Autovaux:
https://www.autovaux.co.uk/ for my Vauxhall parts and they seem to have now broadened out their product range to include other makes. I would buy from main dealers and sometimes, for more expensive items, I'll price match against them before ordering. Most genuine manufacturer's dealer supplied parts come out pricey but I'm sometimes surprised by Fiat so always give them a bell "just in case." The only car in the "Family Fleet" which I find difficult to buy genuine parts for at good prices is the Jazz, so it's been run on Factor sourced generic parts since it was bought around 2012 and seems non the worse for it.
Edit. Sorry I didn't say anything specific about the antifreeze. I just give the vehicle reg no to the factor and he gives me the appropriate antifreeze. Both our Fiats were filled with this when I did their cam belts a few years back and have been absolutely fine. It's an Oat based 5 year antifreeze made by TradeTEC which has now become NAPA following a recent takeover/buyout by the American concern:
https://www.tradetec-oil.co.uk/ I've spent time in the States and used NAPA parts over there and know others who use that brand and they make reliable enough gear - I've no complaints. See Rainman Ray's Repairs on you tube, he seems to work in a NAPA autocentre, very entertaining videos if you like that sort of thing - which I do!
Another Edit. I've just seen John's post above and would add that S4p often give an alternative part to the genuine FCA (or whoever they are these days) part alongside the genuine article. Often it's some "strange name" Original Birth made me very wary the first time I bought a part so branded but the quality is good and when I rang them up I was told that they source many parts direct from Italian manufacturers so the brands are often not those we are used to over here - fear not, they've not sent me a duff item yet. Free postage on orders over £25 last time I ordered and a wee forum discount too if you are a
donated member (you only need to make a small
donation to gain this advantage)
obvs my car is very important to me so if I need to pay for a service its not an issue but do I need to??
