10 replies to this topic

[Slinger]

When checking the oil in my daughters 1983 998 Mini City E, I noticed the oil on the dip-stick contained tiny air bubbles, something I have never noticed or come across before.
It doesn't look like water as there is no sign of emulsion anywhere and the water in the rad is fine. I changed the oil and filter in case the oil was knackered but the tiny air bubbles are back. Just somehow doesn't look right.
Apart from that the engine seems to run as sweet as a bag of nuts with no other symptoms.

Could the head gasket be on its way out or some other problem?

[AlexM]

Do you have oil pressure?

[Slinger]

Seems OK, no oil warning light coming on.

[AlexM]

Are the valve cleareances correct? This can cause all kinds of issues, can hugely affect how an engine runs

[Jammy]

Just a wild stab in the dark, but maybe there is something reacting wih the oil on the dipstick, have you got a spare to use?

[Slinger]

Clearances haven't been checked in a while but tappets sound ok. As for the dipstick - I'll dip it with the one off my Cooper and see what it looks like.

[Sprocket]

How old is the oil? what grade is it? or is it some of that cheap nasty halfrauds recycled stuff?

Oil does boil when exposed to its limits but it is more likely to be fuel boiling out of the oil. Petrol, being a solvent, disolves in the oil when cold( fuel pump leak?), when it is then heated, the petrol starts to boil causing lots of tiny bubbles.

Fuel saturated oil is not a good thing as its difficult to pump. It foams in the pump itself, not to mention that it will foam on the journals at the higher localised temperatures, leaving lack of lubrication. Seveare cases will destroy the engine.

If you could take a sample of the oil in a scientiffic jar then heat it until the petrol started to boil off, it would most likely resemble a glass of Guinness ( not suggesting you actualy do this)

[Slinger]

The oil is 20/50 Unipart green and was only changed last weekend as I needed to eliminate the oil being knackered so you may have a point with the fuel. How would this get mixed with the oil though?

[Sprocket]

The oil is 20/50 Unipart green and was only changed last weekend as I needed to eliminate the oil being knackered so you may have a point with the fuel. How would this get mixed with the oil though?

Fuel pump leak???

[bluebottle]

if you checked the oil not that long after running the car , its quite normal to have bubbles in the oil.

[Slinger]

Maybe I'm worrying over nothing as when I checked the oil before starting it up it looked quite normal but after I had run it for 5 minutes and checked again it was bubbly.

Reckon I'll go and get some beer myself.