2 stroke oil (2SO) as an additive to diesel fuel

[kaanage]

Given what Greg Roles has said about flash points and looking at these and auto ignition temperatures of 2 stroke oils (where these could be found), I now feel I was wrong with my previous hypothesis about the action of 2 stroke oil (and other non-metallic catalyst diesel additives) for more complete combustion and smoother running.

The action would appear not to be more controlled ignition but more complete combustion via the extension of the burn interval, since the flash point of 2 stroke oil is pretty much always higher than that of diesel. This would go along with the clean burning requirements of 2 stroke oils (needed to prevent deposits in 2 stroke engines)

Thanks for pointing us in the correct direction, Greg.

Anyone know of a university needing a doctorate thesis topic?

[CardinalSin]

Better, more complete combustion also explains the reduction or elimination of smoke and the dramatically reduced emissions shown from annual testing in Europe.
I had a quick look for a post on reduced soot levels using 2SO and found this one which i'm sure is a copy and paste from the epic posts about Mercedes using it on Frelander?
If the soot levels are reduced by 50% on a vehicle being tested without a DPF it seems reasonable to assume that on a vehicle equipped with a DPF it should half the number of regens and double the km's before the DPF reaches maximum particle capacity.

"The measured cloud-factor of a diesel engine without use of 2-stroke oil has been 0,95.
The same factor with the use of 2-stroke oil has been 0,47 - reduction of nearly half of the soot particles.
Besides this, the use of 2-stroke oil in the diesel will increase the mileage by 3-5%."

Reducing fuel consumption

There are more references to the reduced emissions.

[Amalgam]

I carried out another observation, but this time on my direct injection petrol car.

Most DI petrol cars have a diesel like clatter at idle. Obviously not as severe as as a diesel, but still noticeable. Especially as the injection pressure increase in newer models as manufacturers chase ever increasing fuel economy and lower emissions. The Toyota GT86 / Subaru BRZ are notorious for this.

After reading the GT86/BRZ forums and the results I had with the Passat, I added a 1:600 dilution of Castrol Activ 2T to my last tank.

The car is my daily driver around town ( the Passat is the wife's ) and therefore the driving conditions can be variable. Approximately 50% free flowing arterial roads and 50% freeway with little to no stop start traffic.

There was a significant reduction in idle clatter but most surprisingly a significant reduction in fuel economy from 7.5L/100km to 6.8L/100km. All the data is from the MFD.

[kaanage]

brad's car is also a gasser. I don't think it's DI, though

[CardinalSin]

Another really good result. I expected the noise reduction from the HP injection pump on the motor but the fuel consumption difference is surprising. That's about the same as you got from the diesel.
The MFD reading as a comparison has to be accurate. The calibration is usually out by 5-10% the same as the speedo but everybody just accepts that it reads a bit over, so 100kph is really about 94kph. Same with the MFD fuel and 5.9L/100km is really about 6.4km/100km. Anyway 6.8 divided by 7.5 = .905 so a saving of 9.5% which is amazing.
Another benefit should be that it will clean the injector tips which tend to get fouled with carbon in DI cars.

Maybe the fuel consumption is a result of reduced friction in the HP pump, piston to bore, valve guides and in time, the cleaning of the system? It's hard to imagine it improves the combustion process in a petrol engine but the results suggest it may?

Here's a site on this topic with loads of nervous skeptics taking forever to try it and then their impressions when they do. I'm up to page 19 and it feels like about 50 have tried it and then commented. Good genuine feedback from people who were expecting very little but gave it a try.

View topic - Interesting thread about 2 stroke oil in diesel fuel | Australian 4WD Action

[Greg Roles]

If the soot levels are reduced by 50% on a vehicle being tested without a DPF it seems reasonable to assume that on a vehicle equipped with a DPF it should half the number of regens and double the km's before the DPF reaches maximum particle capacity.
.

Would help, but the ECU software kicks in a km based regen if it doesn't happen in an "average" timeframe, but you will see maximum regen intervals with good fuel and the right additives, and obviously no inner city driving!

[CardinalSin]

Would help, but the ECU software kicks in a km based regen if it doesn't happen in an "average" timeframe, but you will see maximum regen intervals with good fuel and the right additives, and obviously no inner city driving!

That wouldn't matter if the regen doesn't generate extra soot each time. If it burns enough extra fuel to account for the difference in the fuel consumption that Amalgam got on his Margaret River trip it would have to add about 5L every regen which is ridiculous of course.

[brad]

brad's car is also a gasser. I don't think it's DI, though

EA888 1.8tsi = direct injection.

I didn't notice any reduction in idle noise but it's ridiculously quiet & smooth at idle anyway (from the drivers seat).

I've done 4708km with 2-stroke at varying levels between 1000:1 - 500:1. Average consumption has been 6.5L/100.

The 4564km without 2SO before that I averaged 6.6L/100km so there's not a lot of difference at face value but there are a heap of other variables too.

I will note that on Vortex98, Ultimate98 & Mobil98 with 2SO the consumption is consistantly <6.5L/100 but on V-Power98 + 2SO the consumption is consistantly >6.5L/100.

I just filled with V-Power yesterday & didn't add 2SO. I think 2SO & V-Power might not be good buddies.

Note that I'm currently using synthetic marine 2SO with the TC-3 spec whereas my initial few tanks were mineral 2SO

[brad]

Maybe the fuel consumption is a result of reduced friction in the HP pump, piston to bore, valve guides and in time, the cleaning of the system? It's hard to imagine it improves the combustion process in a petrol engine but the results suggest it may?

I can't see why it would reduce friction in the valve guides - it's DI and the fuel doesn't go near them.

What it might be doing is slightly altering the 02 readings towards a rich mixture and fooling the sensors into running the engine slightly lean. Similar happens when you run ethanol fuels (even E10) in these engines. The O2 sensors read the mixture as lean because of the oxygen released from the ethanol as a biproduct of combustion and the ECU pumps a bit more fuel in.

[CardinalSin]

I can't see why it would reduce friction in the valve guides - it's DI and the fuel doesn't go near them.

What it might be doing is slightly altering the 02 readings towards a rich mixture and fooling the sensors into running the engine slightly lean. Similar happens when you run ethanol fuels (even E10) in these engines. The O2 sensors read the mixture as lean because of the oxygen released from the ethanol as a biproduct of combustion and the ECU pumps a bit more fuel in.

Neither can I, I wasn't thinking clearly when I said that.

If the O2 sensor is leaning the mixture out, would that raise or lower the EGT?

Fantastic fuel economy. What made you change from mineral to marine synthetic when that has been the blend that's been widely reported not to use, based on it's combustion properties being less complete than mineral oil and causing problems such as deposits on the injector tips? Someone was using it on a BRZ/86 and noticed increased deposits on the injectors when they pulled them out again as the seals were causing problems. That's just a specific case I can remember but the warning has come from similar cases I would imagine.