#Shorty : I hope you don’t feel that I’m speaking de haut en bas here. But I sense that you cannot do basic repairs yourself, but rely on garagistes. That, as #mr-reno-139 says, can be expensive and unsatisfactory. If I am wrong in this assessment I apologise.
But if I am right : you need to know that R4s are primitive beasts which were originally designed to be user-serviceable. They are thus much easier to own if you understand, and can do yourself, a few basic maintenance procedures. If you feel you are lacking that knowledge, get a Haynes Manual Renault 4 1961-1986 off the Internet (there are several currently on eBay at about GBP £20) plus a book on basic car mechanics to explain the concepts. Then get a few basic tools (see my previous post) and get going. Changing the oil and filter is a typical "beginner" task and there is satisfaction when it is done. Incidentally the oil is bog-standard 20/50 (no need for semi-synthetic if you change it regularly) and the filter is GFE 210 (or equivalent) for 845cc engines (may be different if you are 956cc or 1108cc).
The problem with R4s, which is certainly the case in the UK and will become more prevalent in France over time, is that few garagistes today have ever seen them and so themselves do not know how to approach what may be a fairly basic problem, solvable with a bit of hands-on past experience.
We are here to help/hold hands if needed. That is the whole raison-d’être of this Forum.
#mr-reno-139 may feel he is being cynical, but unfortunately he is also absolutely correct. And he doesn’t mention one other factor, which is that one does not wish to become known locally as a stupid Brit with more money than sense. My father had a house in France and was just such a fool himself and it has taken me 20 years to expunge that particular local stigma.
NOTE!! When I say “filter” in my two posts on this Thread I am referring to the OIL filter. The air filter will need changing as well but that is a separate exercise (even easier).
