Mazda UK said that no issues will occur with the engine due to the incorrect oil being used and there will be no impact to any future warranty claims if they were to occur.
I wouldn’t expect there to be any issues within the warranty period anyway, but at least I have that in writing.
Interesting, but in my case it wasn’t about the dealer’s choice of viscosity, it was the other oil ratings/specs which are not the ones specified by Mazda for this engine.
Sadly, it’s not the ‘technicians’ that count here I suspect. More likely bean counters trying to save money. Every time I asked they said they had (deliberately) put in RN17 and it was ok, and only important thing was I should top it up with the same viscosity oil. To me that just shows blind ignorance and deliberately not following Mazda recommendations. Hence my ‘shocking’ statement.
Worse still is that their name appears in the Club magazine regularly, which is how I found them.
I have heard similar many times over the years with several other make dealers. Basically customer gets over charged for a cheaper oil, should not be able to happen
They claim to have put in Castrol RN17. Maybe cheaper than the Mazda stuff, but there are many oils that meet the Mazda spec, just RN17 isn’t one of them.
If it is any comfort to you, A5/B5 designation oils are High SAPS oils (sulfated ash, phosphorus, and sulfur) which are what are frequently pointed at when engines get gunked up. They are intended to extend the range of the oil for longer service intervals. The Renault spec oil is a C3 oil which is categorised as Mid SAPS. Castrol actually state that the RN17 oil actively resists and clears the sludge making for better performance and life.
My van has a 50,000 oil service interval and thus long life oil. Most club members oil will be lucky to see 12 months. I would sleep easy.
Yes,thanks, and it’s getting the right oil put in it on Fri. However, presumably there is nonetheless a reason why Mazda chose the spec they did.
What appear to be Engineering decisions are made of very many differing reasons and not all of them may be technically based. It could be that this was the very, very best option and the cutting edge of oil technology at the time. Although the reality may also include that the Engineers have used this oil before, that the production line variants also use this oil in different engines. That specifying a different oil and thus diversity adds cost and complexity in production, storage, tooling and the like as well as “getting a good deal” from the oil company, especially if you are putting 4 or 5 litres in near to a million cars each year.
I suspect the Renault spec oil is actually the “better” oil, but it is not going to matter in the grand scale of things.
So the dealer put Mazda Ultra in and changed the filter. Nice Mazda master tech let me have a look under the car whilst it was up on ramps and was happy to chat. Left me the remainder of the 5L can of oil too.
Thought it was odd they didn’t put bulk oil in. As if they didn’t have any and ordered in 5L of the oil just for my job. Maybe they always use the RN17 for Mazdas? Who knows. Anyway, if I go back to them, I’ll make a point of asking then to use Mazda spec oil 
…
lol, yes, very fishy
Personally I wouldn’t go back again. Only when you got Mazda involved did they do something. Who would potentially want that grief again. If we all didn’t reward stuff like this with repeated custom, they’d soon change when it hit their pockets.
Servicing cost was a lot lower than any other Mazda dealer I could find (£268 for a 2nd service). I guess I know how they can manage that now 