I had a trucker friend that also is a boater tell me he always adds 2 cycle motor oil to his diesel fuel to smooth the engine out in his big rig. Says he swears by it. I "googled" the topic & found varying opinions as to the effectiveness of the practice. The concensus was that it would be good for the injector pump and injectors, would burn away cleanly and even if it didn't offer any real help to the engiine running smoother, it certainly wouldn't hurt it.

Soooooo...I tried it. I added some 2 cycle oil to the fuel with my next fill up. I added enough oil to yeild a 128:1 mix (one ounce of oil to each gallon of fuel). I also added my regular mix of fuel stabilizer. After starting the engine, I sat back and just watched the tiller handle for a few minutes. It was amazing! The tiller handle went from strongly vibrating to almost no detectable vibration at all. As we ran the engine out at higher RPM next time out, we noticed much smoother and quieter operation.

I'm sold! Anyone else ever had any experience with this?

Thomas,

It seems that the older I get, the more I rely on empirical evidence. The "experts" many times have an agenda or stated more bluntly, don't know what they are talking about. I did some research based on your post and came to the conclusion that once again information from someone who has done it has it all over someone who has a theory. Today I added 19 oz. of 2 cycle oil to my starboard tank which contains 19 gallons of diesel fuel. I ran the engine at 1400 RPM which is where I experience maximum vibration. Bottom line is that my original Volvo MD 11, affectionately known as "Old Thumper" liked the mix very much. I noticed the following within about 15 minutes or so.

Noticeable reduction in vibration.

Noticeable reduction in engine noise.

No knocking or detonation when accellerating to higher RPM as previously experienced.

Oil smoke although minor to begin with, disappeared.

In short, instead of sounding like a collection of parts trying to fly in different directions, "Old Thumper" sounds like a smoothly running diesel engine. (At least for a two cylinder.)

I ran the engine under load and stopped and re-started it several times. No hard starting or tendency to run-on when shutting down.

I may have to come up with a new name for "Old Thumper".

Thanks for passing this on. I think I just got a top overhaul for $ 4.00.

Werner

I've never tried it, but I'm going to now!  The reason for using 2-stroke oil would be that it is designed to be burned, whereas other lubricant oils (like a 10/40, for example) are not, and would smoke alot more (probably due to the amount of detergents in the chemical package).  A bit of background... I've been a mechanic for 20 years. 

Fagin

Ralph Weiland wrote:I often add a quart of automatic transmission fluid to a 20 gallon tank of diesel on our two tractors.  Gives a little extra lubricating ability to low sulfur diesel, and burns as well as diesel.

I shared this thread with a friend who has a Perkins 4.108 in a CSY 37. He found and passed along a similar link regarding the use of Marvel Mystery Oil for the same purpose...