Steam Oil

The current oil supplied by Roundhouse is, to use it's correct title, 'Compounded Bearing Oil 220' (220 being the weight or viscosity) and was chosen after consultation with the oil's manufacturer and discussion as to its precise application and working environment. The change of oil was brought about a few years after Roundhouse adopted internal gas firing and a small number of engines were experiencing blocked super heater pipes after prolonged use. The blockages were caused by carbonised oil, though this had never been a problem with the earlier externally fired models. The key points that dictated what oil to use were as follows.

1/ Working on a (relatively) low steam pressure of 40psi.
2/ Displacement type lubricator positioned in cab, so 'wet steam' pickup.
3/ Long pipe run (again, relatively) between lubricator and cylinders.
4/ Small diameter of piping.
5/ High degree of superheating between lubricator and cylinder as superheater heated directly by gas burner and will often be glowing red during operation.

What was needed in this case was an oil that would be picked up and carried by the (relatively) low pressure wet steam, then travel through all the small diameter piping, through the high temperature of the superheater (without being carbonised), and arrive in the correct proportion in the cylinders where it cools again before doing its job.
All of this pointed to a medium weight oil so that it would pick up and pass quickly along the narrow pipes and one with a low 'solids' content so that carbonisation in the superheater was kept to a minimum. The 'solids' reffered to, are additives such as tallow and other fats, which are used as they are a good lubricator in wet conditions.
To deliver the correct amount of 220 weight oil, the feed hole in the lubricator had to be reduced in size as the now thinner oil picked up and flowed far more freely.

We offer the above case both to illustrate the fact that no one oil is 100% suitable for all needs, and to explain why the current Roundhouse oil is so different from it's predecessor.
Please note that using the current 220 oil in an older Roundhouse loco that was originally supplied with the thicker oil will not cause any problems other than an oily engine. Using thicker oil in the current models should not be a problem as far as lubrication is concerned (slightly less getting to the cylinders), but may lead to long term carbonisation in the superheater.

------------------------------------------------------------------------------------------------------------------------------------

 

So, the Roundhouse oil does contain tallow and other fats. I use the Roundhouse oil in all my engines with excellent results. I too find it hard to understand why people will spend thousands of dollars on engines and then cut corners on steam oil.