Diesel Fuel / MPG / Additives / Cetane Rating Question

I have a 1998 Beetle. 5-Spd.

I'm getting anywhere from 43-47mpg. More to the lower end. I was reading the newbie guide to getting best MPG and will start to do some of the free / cheap options avail.

I am currently getting my diesel from a truckstop down the street from my house (on the way to work) @ 4.02$ / gal. If I go up north towards work, it hits 4.50$ and even higher per gallon. The station / Truck stop i'm going to is a Mobile station. I don't see any Cetane rating. I guess worse case its 40 (law's minimum). I was reading BP/Amoco is the best. I have a Chase BP card I used to use all the time for my Avenger 5-spd (Gas).

I was reading that the higher Cetane rating, the better mileage I will see. First question is, does anyone know midwest's Cetane for Mobile stations? Where can I find out? Based on the math, if I spend an extra $0.48 / gal, and get my ~5mpg (48-52mpg), I will be about breaking even. BUt the fuel itself will be better for my intake, engine, etc. So to me, its a wash and has the advantage with better fuel. Make sense? And worth it? And anyone have the info on Mobile? I'm all for BP fuel. Use it religiously for my Ram 1500 (2005 Hemi). And Avenger which sits not driven due to my TDI!

Second, even with the BP fuel (if its really over 50 Cetane), should I still put additives in it? Or am I just then wasting money? How much does a bottle cost to treat 14.x gal tank? And what do you recommend? Do they have any kind that will obviuosly treat the lower Cetane fuel, but also clean injectors/intake? Would be nice to do both in one shot.

And then next question, what would you recommend to clean injectors/intake? How often should I run it through a tank of gas? Like, every 4th fill up or? Any tips would be appreciated. Or points in the right direction/links! Thanks.

__. Kevin, additives are made to increase cetane, provide added lubricity (a sore point since the change to ULSD a little over a year ago), and clean parts (pump, injectors, etc.).

__. If I were in a place with higher cetane, I'd still run additive for the lubricity and cleaning properties. But I'd buy a less-expensive additive that didn't have so much cetane improver.

I suggest that you do some personal testing. Try both fuels and compare what mileage YOU get in YOUR car. Other may get different results. Increased cetane will increase mileage under some conditions, but it will not always do so. So just see what it does for you.

As for injector cleaner, I would suggest that if you use the best cleaner often, you are not likely to have a problem. If you don't use any you are not likely to have a problem. Maybe very slightly less likely to have a problem using the cleaner. I am on my second diesel. The first made it 180,000 miles before it was totaled in an accident (no injury) and it never had injector problems nor did it ever get any cleaner above what was in the fuel. My current diesel has never had a problem (about 75,000 miles so far) although it has had a bottle of fuel winterizer along with cleaner in the fall each year.