Bad Gasoline

[bcfitzsimons]

Well, in a quest for information as to why my 15000 mile 8.1L would develop deposits in the cylinders/on the pistons that would create cold start knocking, I asked around and did some armchair research.  Naturally, the first thing I'd start looking at was gasoline quality.

 

The answers I got were very interesting.

 

A good friend of mine (who actually used to be an engineer for AC Delco before he joined a private firm) talked to some people he knows in the lube business.  Apparently, the gasoline marketed by BP in the US is refined from pure North Sea crude, which has a very high content of paraffin (i.e. WAX).  Now, there's no way BP is able to refine all the paraffin out of its gasoline . . .

 

Which may explain why my local dealer told me he was happy my Top End Cleaner adventure worked-and that my cold start knocking was due to deposits in the combustion chambers.  This dealer's head mechanic told me that a lot of the fuel system problems they're seeing recently are probably due to gasoline quality, and just because you have low miles doesn't mean you have a clean motor.  He said that they replaced three fuel pumps and a number of injectors on 3 different Chevy Tahoes last week, and the only thing that ties these 3 vehicles together is that the owners used BP gas exclusively.  Of course, he says " . . . now I can't recommend one brand over the other officially, but you can put two and two together . . ."

 

Now, my engineer buddy says that Royal Dutch/Shell, Sunoco, and (in the Midwest) Marathon all use sweet crude from the Middle East, and no North Sea crude, so paraffin levels are low.  He also said that CITGO does NOT buy crude from the Middle East, but he does NOT know if they buy crude from the North Sea.

 

I'm going to see if I can find out anything more.  Needless to say, after my experience (and I used only BP gas), I'm going to be cancelling my BP card and getting a Shell card.

 

Anyone else care to share any gasoline wisdom?

 

Fitz.

[kc2aku]

I think your a little confused by the term paraffin.  Here is a link to kendall motor oil's web page explaining it better than I can.

 

http://www.kendallmotoroil.com/techtips/default.html

 

I also have posted the text in case the link doesn't work.

 

Your Oil Contains Paraffin - I Can't Use It ...... or Can I?

 

There is a myth among motor oil users that all paraffinic base stocks contain wax that causes engine

sludge -- if this myth was true, neither we, nor any other oil manufacturer, would be in business. We all

use paraffinic crude oil in manufacturing motor oils. Invariably, the word Paraffin means wax to most

people. Actually, the word means little affinity or inertness (slow to react or little change in respect to

temperature).

 

When subjected to chemical analysis, crude oil has little chemical affinity -- thus it is dubbed paraffinic.

There are various amounts of wax present in crude oil and it separates from the crude oil upon

cooling. The wax also resists chemical reaction, due to its affinity, and is appropriately called paraffin

wax.

 

The crude oil is refined and dewaxed to remove the wax forming compounds that improve cold

temperature properties. We add pour point depressants to further enhance the low temperature

properties of the oil. Kendall's advanced refining technology produces an even higher quality base

stock than in years past. A superior blend of our high quality hydro-treated base oil and premium

additive package provides Kendall customers with greater oxidation and thermal stability, excellent

deposit control and wear protection. This all translates into longer engine life and unrivaled savings

for you.

 

Okay, the base oil has been refined -- now would you like to know the next process in providing you

with High Quality Kendall Motor Oil? Be sure to check out the next "Tech Tips" for the answers. Until

then .......drive safely.

 

 

If you have any questions concerning the proper engine oil for your vehicle or it's proper care, E-Mail

the Kendall Engineers or call the Kendall Sales Engineering Department at 1-800-368-1267.

[99silveradoz71]

Fitz, that neighbor with the 2000 Sierra that had injector issues due to BP gas said the dealer indicated Shell and Marathon are the 2 recommended in our area for our trucks.  I usually use Sunoco, but maybe 2 or 3 times a year, Shell may get the call.  No problems to report.

[RyanbabZ71]

I have heard that shell gas contains sand (small amounts).

 

I ran shell gas for about a yr then switched to mobil

 

Best gas i have run was chevron on my trip to NC (we dont have chevron around here).  Got my best mpg and my truck drove great

[Shaners]

 The only gas we have in my town are BP, Citgo, Sheetz and KwikFill.  There is a Pennzoil station about 5 miles from here...  

[carguru]

I have heard that shell gas contains sand (small amounts).

 

I ran shell gas for about a yr then switched to mobil

 

Best gas i have run was chevron on my trip to NC (we dont have chevron around here).  Got my best mpg and my truck drove great

The other alternative would be to use Texaco.  Texaco and Chevron are the same companies.  In Raleigh area, there are no Chevrons.  There was a study done by BMW some years ago on gas quality.  What they found was that Exxon and Chevron were really clean.  All the others tested were much less clean by a large margin (I believe BP came in near the bottom).  The criteria for the tests were deposits on valves and injectors after a given number of miles.  I'll have to see if I can dig that old report up.  This report was put out in the late '80's early '90's before all of the companies merged.

[bcfitzsimons]

It's a pity there's no Exxon/Chevron/Mobil stations in NE Ohio.  I suppose that Shell, Marathon, and Sunoco are going to be getting my business from now on.

 

99silverado-I remember you telling me about your neighbor who had to have his fuel injectors replaced because of BP gasoline.  

 

Has anyone else had any bad experiences with poor quality gasoline (beyond the occasional knock)?

 

KC-I'm talking about gasoline with paraffin wax dissolved in it;  not motor oil.  Paraffin wax collects differently on valves and cylinder walls when its atomized and then burned as opposed to circulating in engine oil.

 

Fitz

[k1500chevy97]

I use Conoco 90% of the time and the rest of the time Chevron .

No problems yet .  

[BlueRado]

Early this Summer, my best man and I got together in Western PA for our annual BS camping session where we sit around camp and drink beer, solve world problems, and eat food that's not good for us . . . anyway, that' another story, but I did fill up w/ an off brand of fuel in my '99 5.3L.  Ran fine the whole trip, and after the 350 mile trip home, the next morning I had the dreaded cold start knock/tap.  I had ~ 40K miles on it , and this was the first time I ever heard any cold start noise.  Kinda startled me.  Also noticed that the engine seemed to hesitate a lot, and in general ran poorly.

 

So I proceeded to fill up w/ a tank of Mobil (my usual in SE Michigan) and ran the crap out of it over the next week, and it cleared the problem up.

 

I am beginning to think there's more to this gas issue than I thought.   ???

 

Anyway, thanks for the info bc!  

[Pancho]

Any information or experience with Phillips 66?

[bummed-n-Md]

There may be something to this...

 

I have been using almost exclusively AMOCO (A BP 'partner'), however on road trips I sometimes fill up with what ever is at the nearest exit to 'Empty', but even then, I only use 'name brands'.  I just checked some of my fuel receipts and it seems that I've always gotten the best mileage after I filled up with Texaco.

 

My neighbor claims that he started using Texaco exclusively in his 2002 silverado (6 cyl, standard, 4x4)  and saw a 3 to 4 mpg improvement.

 

I thinks to time to try some 'semi-controlled' experiments.

 

 

[carguru]

Any information or experience with Phillips 66?

I'm using Phillips 66 or Texaco most of the time.  Haven't had any problems.  However, I religiously run a bottle of Techron every 3000 miles.

[bcfitzsimons]

I agree, bummed-MD.  Supposedly the pistons used in these new Vortec blocks, along with the heads, were designed by manufacturers that make components for racing engines, and the stuff they sell to GM is very similar.  Stuff is designed with different tolerances, and different metals (e.g. hypereutectic pistons).  Considering new generation fuel injection, emission controls, electronic tuning/timing, and all the other redesigned components, it's not surprising to me that gasoline quality plays a far greater role in engine performance now than it has in the past.  

 

What we need is objective data.

 

Fitz.

[woyster_00z71]

With my 2000 Silverado, I used to fill up at Sam's Wholesale Club because the fuel was between $.08 and $.18 per gallon cheaper.  I noticed that the truck was pinging badly so decided to use Chevron gas and the pinging stopped.  Ever since then, I pay the extra pennies and use Chevron exclusively.

 

On the other hand, the Sam's gas doesn't seem to bother my 1997 truck so I save the pennies there by not using Chevron.  Every once in awhile I put in some fuel system cleaner just for good measure.

 

B.J.

[bummed-n-Md]

I used to use Chevron exclusively in all of my vehicles, but a couple of years ago, Chevron pulled completely out of this area and all of the stations are now either BP or AMOCO.