Engines (1) Oil Change

In a previous article, I'd begun to describe the engine oil change (but got distracted on to other oily activities!). Mid-July 2013, I did the oil change on both front and rear engines. The front engine had been topped-up with used (not too clean) crankcase oil (a rather unsuccessful attempt to fling it about by rotating the engine on compressed air. All I'd achieved was to introduce a load of sludge into the works!). The rear engine I'd drained off partly in 2009. I hate to imagine when the last oil change had taken place!

Oil filler 'cap'

Like on most internal combustion engines, there is an oil filler 'cap'. I'd read that each engine needed 10 gallons of crankcase oil so enough had been bought earlier back in 2010 (when I thought it might take less than a year to get 7109 back to life - How wrong I was!).

The crankcase oil is Hallett's Sentinel Crankcase Oil SCC680. It is a viscous oil (ISO 680) and has the specific property of enabling water to separate from it and readily sink to the bottom where there is a drain valve to let it out. This water separation property is important with a Sentinel steam engine which inevitably encounters condensation in the crankcase. (Morris Lubricants also make an equivalent crankcase oil for Sentinels).

Expecting to use 10 gallons per engine, I decided I would log the amount added against the level indicated on the dipstick.

I filled the front engine first with these results:

1 gallon: Not on dipstick.
2 gallons: 1/4 on dipstick.
3 gallons: almost 1/2 on dipstick.

I added a couple of extra litres to make it 1/2 full. (I like to mix imperial and metric units!).

Then the rear engine:

1 gallon: 1/2 on dipstick!

Oddly, I didn't expect this as none had been added since emptying.

So why did the rear engine need 1 gallon and the front 3 gallons to be half full? Simply, I don't know! However, I have to conclude that there must be something that isn't oil also in the rear engine (which was the one without the sludge added!).

Perhaps inadvisedly, I'm not going to investigate this further for now but monitor it very carefully when initial testing begins.

As yet, I also don't know whether is it is best to fill to the top of the dipstick or not. At least there is some spare oil available!