I was wondering if there is a difference in quality of diesel fuel between companies? Does it matter as much as regular gasoline?
When I had a gasoline vehicle I would never put in cheaper gas (such as gas from a rebel, 7-11, or Circle K), but would always go to a Chevron or Shell. I knew I paid a little bit more with each fill up, but the benefit to my vehicle out weighed the cost.
Is there also such a factor with Diesel fuel? Should I just fill up where it is cheaper or go with a more reputable gas station like Chevron or Shell?
I'm curious what findings other people have, but for me, I've noticed in my wife's TDI Jetta, going to a cheap station results in bad performance/economy and we had to replace clogged fuel filters every few months. We've stuck with major label brands and haven't had problems since.
There are significant differences in diesel fuel btu's (the amount of energy contained in the fuel) and that is why airplanes measure fuel by weight, not by gallons. The btu's per pound are more or less linear at something along the line of 18,700 btu's per pound if my memory serves, but by gallon they vary by quite a lot depending on the fuel density. Heavier fuel has more energy per gallon than light fuel does.
As for variances in brands, I've noticed that many "name brands" sell diesel refined by refineries other than their marquee. Texaco used to sell a lot of G&M diesel here in So. Cal. there was a small sticker on the pump that noted the difference, but not all the Texaco stations used G&M so the user had to check carefully at a station that they didn't normally use. As Mathowie pointed out, the additives and impurities can have an effect on performance, mileage, and your fuel system parts like filters and injectors so beware. In Mexico I used to buy marine diesel (sold at boat fuel docks) for my old VW diesel if I had the chance, it seemed to work better than the PeMex road fuel sold to truckers.
All fuel that goes thru the pipe line shares the same pipe. First they may send 1 million galions of unleaded thru and then 1 million gallions of diesel. The measure what they get out vs what they put in. Of couse in the middle there is a mix of Diesel/ Gas. When it gets stored the fuel settles out and they can get out what. Higher Octane gas is usually just additive they add while filling up the trucks. There is also 2 tiers of fuel per station. A PB station might get the cream of the crop, like the non mixed fuel while the mom and pop migth get the slightly mixed stuff. A guy that works for the pipe line told that to me. Very intersting. I might be off a bit but most of is what he said.
I have a Fiat 500 diesel, and had problems with my car spluttering when I filled up at supermarket stations. Now I solely fill up with Shell or Esso (regular diesel) and have had no problems since. It's a much smoother drive too.
The quality of the additives in the fuel has a strong effect on the quality of the fuel. What you tend to pay for with the premium brands is less of more expensive additives & some/better detergents. So yes while Tesco's 99 RON fuel is higher octane than Shell 98 RON, however the Shell fuel gives you more energy for the same volume (it's up to the ECU to work out if you can take advantage of that however) & the same applies to diesel.
Fuel in America is generally unrefined, hence why you may have problems running European diesels or petrols on US branded fuel. Gas/diesel is more refined in Europe due to the higher emissions standards etc, but we also pay a much higher price for fuel. Try running a 600 BHP Vette on our gas and test the BHP then, you'll see an increase!
actually our diesel emission standards are now higher here in the US. We now have low sulfur diesel and some cars are using Urea to conform to the higher standard. Some reasons why we are not getting the good euro diesels is that it cost a lot more to in equipment to pass our standards here in the US. Only a few years ago it was the other way around. Go figure.
I'm having the same debate with myself at the moment (!). I've used Shell V-Power (high performance) diesel and while that results in a quieter engine and, in my perception, better throttle response, I get better MPG from the regular diesel.
I always believe you get what you pay for but as i'm using a premium brand fuel and paying slightly less, i'm struggling with the facts.
Finally, in the UK we really do have cheap fuel and premium fuel although i'm led to believe that it's the additive package added that makes the difference compared to supermarket/budget fuels that have a poor package or none at all. My retired parents always filled up with supermarket fuels but since having to make a distress purchase of BP due to running low, they always fill at BP.