Author Topic: REDEX Fuel additive for SKYACTIV-G  (Read 86 times)

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Offline john_severn

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REDEX Fuel additive for SKYACTIV-G
« on: November 20, 2020, 05:25:26 PM »
Hi Everyone,

Wondering if there is any wisdom out there concerning Redex petrol additive and using it with SKYACTIVE-G 2.0 petrol engines.  Good idea or only use the very expensive Mazda fuel additive?


Offline Engineer Andy

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Re: REDEX Fuel additive for SKYACTIV-G
« Reply #1 on: Yesterday at 12:59:04 PM »
It'll make much less of a difference (presumably the fuel injector cleaner) on the direct injection SA-G engines in gen-3 cars and newer than for the port-injected gen-1 and 2 cars. The fuel + cleaner would help clean the inlet valves, but will barely do so on the newer cars.

I'm sure it'll make some difference to the injectors on the new ones, but only those cars doing predominantly short trips from cold on a rich mixture where deposits of unburnt fuel/carbon may build up.

I buy a 4-dose (500ml) bottle every couple of years on my gen-1 1.6 petrol car when they are on offer at Halfords (normal price about £8-10, offer about £5 last time), using 2 doses over the next two fill-ups, then repeating 6 months later.  Seems to do the trick for mine.

Even without the offer, it's still far cheaper than using branded superunleaded fuel (which apparently has extra cleaning additives over both normal supermarket unleaded and super), which is about £6 a tank more expensive for a similar effect as one dose.

Cars will get more of a benefit from the higher octane rating through better mpg (even if the injectors are relatively clean anyway) or performance, but only to a few percentage points - mine achieved about 2-3 better mpg, but obviously only when I was using that fuel.  Cars with clogged injectors will get similar better running once the blockages are removed.

I'm not so convinced about car manufacturers' own brand of things like this.  Unlike 'brand name' items like Redex or consumable parts, like windscreen wipers, Mazda won't give discounts, but will likely be similar to brand name ones - like Bosch wiper blades, which I can source on either ebay or Amazon for nearly half the price Mazda of (incidentally) Halfords (who rarely discount on that item) would.

Unfortunately the way direct injection engines work, they are more likely to get gunk on the inlet valves than older, port injected cars.  It doesn't appear to be a huge issue on Mazdas as few have reported knock-on problems such as apprecably reduced mpg or rough running - and probably only those doing the type of usage pattern I described above.

If you do a decent amount of longer journeys where the car has time to warm up and run at decent speeds, then I'd only give it a dose or two or Redex or similar every few years.  Badly affected cars can apparently have soem walnut blasting treatment to remove caked on residues in addition to having the injectors cleaned/replaced as necessary.  I've yet to hear of anyone here who's car has needed that level of cleaning though.

Mazda 3 Forums UK

Re: REDEX Fuel additive for SKYACTIV-G
« Reply #1 on: Yesterday at 12:59:04 PM »