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Quote: Originally posted by cbreddie on 17/1/2015

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We used to fill up at tesco for years. we had loads of issues with engine management lights coming on. Since we swapped over to Shell or other better brands we havent had any problems.....

Now before you all shoot me....

We have ALSO changed the type of mileage the car is doing. Our car is a Mazda6 2.0 diesel and we were doing mainly around town miles.... but in the last two months we have started doing about 200miles per week just on the motorway.

So maybe the lights on the dash were not caused by supermarket fuel.... I guess we will never know.

So my post is utterly inconclusive but then again the whole subject is impossible to prove as one cant generalise, because there are so many variables, IE....

Type of fuel (diesel or petrol)
make of car engine
type of mileage
style of driving
what weight is the car carrying
climate variances (temperature, humidity and the like)

There are lots of different combinations and the only way to see a difference is to try it out for yourself with the set of your own (combination of variables).

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Quote: Originally posted by charlichoo on 18/1/2015

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We have 20+ vans at work all doing around 100,000 miles a year. Half have Shell fuel cards and the other half have Genie fuel cards so get filled at Tesco or Morrison's.
The vans running on Shell fuel return better mpg and have less engine problems than the vans using the supermarket fuels.
The most common issue is that the fuel filters need changing more often on the supermarket fuel vans as they get "gunked" up! The shell fuel vans do not have this problem.

I fill my own car with Shell fuel.

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Quote: Originally posted by Taylor56 on 18/1/2015

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Quote: Originally posted by cbreddie on 17/1/2015We used to fill up at tesco for years. we had loads of issues with engine management lights coming on. Since we swapped over to Shell or other better brands we havent had any problems.....

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Now before you all shoot me....

We have ALSO changed the type of mileage the car is doing. Our car is a Mazda6 2.0 diesel and we were doing mainly around town miles.... but in the last two months we have started doing about 200miles per week just on the motorway.

So maybe the lights on the dash were not caused by supermarket fuel.... I guess we will never know.

So my post is utterly inconclusive but then again the whole subject is impossible to prove as one cant generalise, because there are so many variables, IE....

Type of fuel (diesel or petrol)
make of car engine
type of mileage
style of driving
what weight is the car carrying
climate variances (temperature, humidity and the like)

There are lots of different combinations and the only way to see a difference is to try it out for yourself with the set of your own (combination of variables).

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If your exhaust has a particulate filter on it(don't know whether yours has or not),they get clogged by short runs and need to be regenerated by a high speed motorway run.If it gets too bad it has to be cleared at a garage.

The wife's last 2 lease cars have been run totally on supermarket diesel(she works for one at the moment)and have not had a problem in 5 years.
Having said that my old Convoy does seem to like Jet diesel better than any other.

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