TC-W3 vs JASO FC/FD as fuel additive in a diesel engine

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Sep 10, 2023
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Since most discussions about using two-stroke oil as a diesel fuel additive seem positive or neutral, I decided to give it a try. However I can't decide which oil approval would be the best choice or if it matters at all.

On BITOG, many people recommend TC-W3 oils, while European forums suggest API FC + JASO FC + ISO-L-EGC oils. However, wouldn't JASO FD + ISO-L-EGD be better due to extra detergents?

While TC-W3 may be better for certain exhaust equipment like TWC and DPF, since it contains no ash or metal additives, I believe JASO and ISO oils could perform better in a diesel engine due to the high temperatures clearing out the small amounts of ash, unlike in outboard engines. There are some concerns about zinc in these oils causing deposits in injectors and DPFs, but I wonder if it is a practical problem given the dilute mixture? I plan on using a 1:200 ratio (0.5%), as this seems common in European forums.
 
The cost of a gallon of TCW-3, coupled with the lack of significant metallic additives, was the deciding factor in my choice to send samples out for Jet-A, HFRR lubricity testing. While it has been nearly 20 years since then, and I no longer exactly remember the results, the results were impressive. Jet-A without additives was terrible, at 650 or so, with stanadyne lubricity additive, somewhere near 450 and Jet-A with Stanadyne along with 200 to 1 TCW-3 was 255 (that number I recall with accuracy). Lower wear scar size is better.

So a number of us used somewhere near 6500 gallons of Jet-A in our older stationary diesel engines with perfect results. I did note a touch of oil dripping from the exhaust pipe on one setup that had a horizontal exhaust discharge, but that was over many hours.

Note: It is generally said that diesel fuel with an HFRR of above 460 does not provide sufficient lubricity.
Note 2: Lubricity is generally for high pressure fuel components, which can fail rapidly with the wrong fuels.

The cost of TCW-3 Pennzoil semi-synthetic was about $15 per gallon, purchased at WalMart, at the time. Even back then, excellent quality FC rated two stroke oil, such as Castrol TT-S, was near $9 per pint or about $72 per gal.
 
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I use any 2 stroke oil at 1:150 ratio, and my injectors are definitely quieter! Had to fill up two times while in spain and didn't have 2 stroke oil with me and the 2000-2500 rpm clatter under load was back until the next fill up with 1:150 2 stroke. Could have been the fuel sold at the Repsol stations but it is more likely to be due to the lack of 2 stroke oil.
 
Choose any ashless option. That will eliminate the JASO products. All TC-W3 oils are ashless but not all ashless oils are TC-W3.

As with all things in life... read the label.
 
The two-stroke oil that I could source is from Motul and funnily enough their outboard oil comes in 25% more expensive compared to their bike oil.
I'm comparing Motul Outboard Tech 2T to Motul 510 2T. The former is TC-W3 and the latter is JASO FD.
If I'm going for outboard oil, is it worth going for semi-synthetic over mineral?
 
I’d use an JASO FD oil - meant to burn cleanly and not leave much behind. Case in point - Stihl 2 stroke engines. Husky XP Plus burns clean and the spark arrestor screen hasn’t built up carbon. Compared to TruFuel and Stihl’s oil that did leave behind carbon.
 
does the semi synthetic claim low-smoke? PIB is the synthetic component that reduces smoke, it's worthwile if you have a DPF
Just found out Ravenol makes TC-W3 oils too and their semi synthetic outboard 2T oil contains esters and PIB!
I'll see if I can source it, thanks for the tip.
 
What sort of exhaust does your diesel have? Does it have a particulate filter or any sort of catalytic converter?
 
What sort of exhaust does your diesel have? Does it have a particulate filter or any sort of catalytic converter?
I have 2 catalytic converters and no DPF.
Also a muffler delete if that matters lol.
 
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