The cold weather start system became standard on German Aircraft. It pumped fuel into a small tank which when full would be emptied into the oil sump at the proper mixture ratio.

Yeah I can hear you say that but that's beside my point which was the original agenda by mixing fuel in the oil towards the end of BoB. If you know anything about engines and oil you also know that dilluted oil, or thinned out with petroleum, decrease its lubrication capabilities up until the temps get high enough to ventilate the petroleum. It was a compromise to improve reaction time. Interesting to hear that it became standard with a mixing tank on German aircraft, do you have any references on that?

When the engine is at lower temperatures, a lower viscosity oil is desirable to keep the top end lubricated.

That is the purpose of the fuel, to lower the viscosity. As the temperature rises, the fuel is vaporized and vented leaving the oil at its pre-mix viscosity.

I honestly do not understand the point you are trying to make.

It is a measure to reduce wear on the engines, too.

Why do think they recommend pickling over ground starts and runs for aircraft engines today that experience more than a few weeks without being flown?

The best thing you can do to keep an airplane healthy is fly it. One of the worst you can do is ground run it up over and over without flying it.

That will cause corrosion and reduce the engine life faster than just letting the airplane sit.

It is as I stated, you simply do not just lower the engine oils viscosity when you mix gasoline products in it. Gasoline also acts as a solvent and that includes decreased oil film pressure resistance, like shear stress and tensile stress capabilities. It doesn't reduce wear in the sense that thinned out oil, using gasoline, works as a lower viscosity purpose refined oil, it makes it more fluid. What you do is that you only lower the viscosity but in the same time you alter its characteristics needed for other things besides flow. That's the difference.

It was good enough for the engineers to include it as the standard winter starting system on all Luftwaffe aircraft.

You can look in Teil 7 of the Flugzeug Handbuch for the FW-190 series for a more complete description.

Germans did not use natural petroleum fuels.....

Their avgas is more like a light oil with a distinctive burned coal smell to it. We have a few gallons to give White One's cockpit an authentic smell, LOL.

It was good enough because it was wartime and things had to be done. That doesn't mean it wasn't a compromise.

Avgas still needs to work as avgas, all gasolines are basically petroleum(oil) products, the biggest difference between oil and gasoline are additives and destillation. For a gasoline engine to run you need fuel with higher energy than oil, for that you need to add ingredients to it. Those ingredients usually also make it work as a solvent. Even though they had a "light oil" etc. they still had to use something that worked as gasoline. No chance in hell those engines put out their full output on "light oil".

While the fuel - oil mix certainly isn't good for the engine, it probably is still better to use it once every two weeks than having the engine being started up every hour for two weeks straight, only to be used once. Also, fuel is only one thing saved, it also saves a load of man hours, which is just as important.

I'm honestly confused about the point being argued :-P

From where i'm standing the whole thing reads like "we don't want to burn fuel warming up every hour, so we just use oil dilution to cut out the warm-up time from a possible scramble sequence".

Compromise or not, it was considered a good enough practice that most if not all USAF warbirds had an oil dilution system as well.

Well, my point regarding fuel was that the oil/fuel mixing stuff on the western front started as a fuel saving measure. Which two of you didn't believe until(hopefully) I posted a direct quote, and from there it went the usual forum way. Picking out one liners from my posts to find something else to argue etc. Either way, I'm done with that topic yo. Let's go back to how the LW got butthurt over BoB 'ol chaps!

Ah, i see...you were arguing the reason behind it while i read it as "fuel savings is a direct consequence of oil dilution"...in any case it makes sense now, cheers :grin: