Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Got a Roundhouse Katie for Christmas and while getting ready to fire it up thought that I'd better read through the instructions just in case I'd forgot something over time. I was surprised to see that 20W50 oil was recommended for external linkage and bearing lubrication now - don't seem to remember that in the past with my other engines. At any rate it seems a little too high viscosity but I'm sure they're smarter than me about such things - what are your thoughts?

There is nothing wrong with a good high grade synthetic motor oil for all parts except the internals of the steam cylinder and chest which of course uses steam cylinder oil.

I use Mobil One 0W-20 and 0W-16 on most of my smaller engines. 20W-50 should work as well but offer just a tad more resistance on the moving parts. I like the lighter weights because it helps me run a model engine as slowly as possible and with as little pressure as possible without stalling.

This oil in spite of any additives does not gum up. I can leave an engine on the shelf for 3-4 years after lubing with Mobil 1 and it is still ready to run and is not gummed up. I learned about it from my friend and master model engine builder John V. McDivitt. It is all he used in his model engines from the time it became available. John began using Mobil 1 in all his engines from it's introduction in 1974. He continued using it even after 1998 when they changed (cheapened) their formulation methods and used it right up until he passed on in 2008.

Here is a brief discussion from wiki:

Mobil 1 is a brand of synthetic motor oil and other automotive lubrication products. Originally developed by the Mobil oil company, and is now globally marketed and sold by ExxonMobil.

Mobil 1 engine oil was introduced in 1974. The brand range now includes a variety of engine oils, oil filters, chassis grease, transmission fluids, and gear lubricants.

In 1998, Mobil sued Castrol over the discovery that Castrol was processing conventional oil and calling it synthetic. At the time, Mobil 1 was still created using a true synthetic basestock, which is more expensive. Mobil lost the lawsuit, and, as a result, the "new" definition of 'synthetic oil' became much looser. In order to stay competitive, Mobil needed to downgrade their process to the more affordable process. The result is a hydrocracked, hydroisomerized conventional oil. Lubes N' Greases magazine has reported shortcomings in the ability to pass the tests that the original Mobil 1 formula was able to pass.

That is a nice Christmas present to get Larry!!, i think the Katie is my favourite of Roundhouses's locos, a close second would be the Lady Anne.

I have done some more due dilligence.
It seems the closest thing to the original Mobil 1 is likely the Amsoil Signature series.

Mobil 1 Extended Performance series approaches it but the Amsoil Signature Series gets better ratings/results in multiple tests.

I will migrate towards Amsoil going forward.

Gil