Fuel additives

I don't think with the tolerances in these pumps it matters. But in use 1 qt of 2 cycle oil in every 35 gallons of fuel in my dodge. 220,000 miles and 18 years with no pump problems. Average life on my style pump is 150 k. With machines that sit around, I think the larger problem would be black sludge that forms in the tank. It is exacerbated by water being present. Your filters will be coated with a black slime. It is time to drain and clean your main tank when that stuff forms. I never add more fuel than needed for the job.But then, an empty tank causes more condensation. Cant win. I live in the desert so moisture is less here.

Hi, oldbeek.
As I understand it, that 'black sludge is an algae that can grow in diesel fuel and can be stopped with an anti-algal additive.

Just my 0.02.

Here's an actual scientific study someone did on that. 2 basic things to learn here: 1) Marvel Mystery oil is garbage and is significantly worse than nothing, 2) 2 cycle engine oil is the only thing other than a proper diesel additive with any positive effect at all.

Unfortunately they didn't test ATF, but people who rebuild injection pumps say it is abrasive and to never use it.


[attachment=55282]HFRRtesting.jpg[/attachment]

Back in the early 1990s, I flew a Cessna 195 with a 300 hp Jacobs radial engine. These old, low-compression engines called for 87 octane aviation fuel which was no longer available and only 100 octane low lead was available. I was advised by the previous owner to put TCP fuel additive in every tank of gas to reduce lead build up and to run a pint of Marvel Mystery Oil per every 60 gallons on every third fill-up to lubricate the top end. I put 300+ hours on that airplane and the compression never decreased. I have no clue whether that was because of or in spite of the oil.

I've been told Marvel Oil is just ATF in a fancier can. Looking at the chart above and the results each oil gets, I now believe it.

I can only state from my personal experience, NOT from what 'someone's' test showed. :lalala: I've used Marvel Mystery Oil (MMO) for years in just about anything with an engine and always gotten many more miles and hours of use than the average. My dad was a mechanic (not a 'tech') all his life and swore by it.
I also use their 'air tool oil' in all our air tools with great results.

MMO was designed for 'top end lubrication' when mixed in fuel...which is exactly what 2 stroke oil does for a 2 stroke engine.

What exactly was this test testing? Better performance? Better fuel economy? Longer engine life? :noidea:

Hi, oldbeek.
As I understand it, that 'black sludge is an algae that can grow in diesel fuel and can be stopped with an anti-algal additive.

Just my 0.02.

[quote="Deas Plant."]Hi, oldbeek.
As I understand it, that 'black sludge is an algae that can grow in diesel fuel and can be stopped with an anti-algal additive.

Just my 0.02.[/quote]

it is a film forming algae. and diesel biocide does treat it. prevention is to keep your tanks near full less condensation equals less chance of bug growing. grandad always reckoned if you fuel up at the end of the day you would get less moisture in the tank overnight since moisture makes the algae worse.

I just use diesel in my diesel and keep the tanks full : ) The local shop does have non-ethanol 87 so I use that in the Briggs lawnmower and my car but still seem to need to replace the plastic Briggs carb every two years.