Old oil in engine

[pcatterall]

On board in Spain for summer preparation decided it was time for oil change as not done since pre covid though only a few hours run.
The old oil seemed thin compared to the new and the engine seemed a little smoother.
Checked the log and found to my horror that it was 6 years since last change though less than 100 hours run.
Will.oil.in engine in Spain degenerate in that time scale.?
I.usully change oil every year but have administered a kick on my own backside for my negligence!!!

 

[coopec]

"Unlike other fluids in your car which have an long lifespan like coolant and brake fluid, motor oil does have an expiration date not too far down the road. Motor oil will eventually break down and lose its effectiveness, even if it's never been used".

https://www.autozone.com/diy/motor-oil/does-motor-oil-expire

 

[vyv_cox]

The hydrocarbon oil itself does not deteriorate but the additives that may make up 20% of the total can have limited life.

 

[Boater Sam]

Worry not, 6 years is nothing.
It spent thousands of years below ground.

I have had engines 70 years old that have never had an oil change, they still work.

 

[Irish Rover]

Worry not, 6 years is nothing.
It spent thousands of years below ground.

I have had engines 70 years old that have never had an oil change, they still work.

 

[Boater Sam]

And your unspoken point is?

 

[penfold]

Worry not, 6 years is nothing.
It spent thousands of years below ground.

I have had engines 70 years old that have never had an oil change, they still work.

The bearings in those engines will be in terrible condition; oil is cheap, engines are not.

 

[Bilgediver]

On board in Spain for summer preparation decided it was time for oil change as not done since pre covid though only a few hours run.
The old oil seemed thin compared to the new and the engine seemed a little smoother.
Checked the log and found to my horror that it was 6 years since last change though less than 100 hours run.
Will.oil.in engine in Spain degenerate in that time scale.?
I.usully change oil every year but have administered a kick on my own backside for my negligence!!!

The oil may become thinner with fuel dilution if your injector pump is mounted within the sump

 

[oldharry]

The oil may become thinner with fuel dilution if your injector pump is mounted within the sump

Also, engineering in those days was agreat deal more basic with much more generous tolerances - you only have to think of the old Seagull Outboards....

 

[Boater Sam]

The bearings in those engines will be in terrible condition; oil is cheap, engines are not.

Are you sure? Is there a good reason why the bearings suffer if filtered old oil passes through them? There will be no metal particles if the filter and possibly a magnet is still collecting them. Carbon from combustion is actually a lubricant. Increased acidity will have a minimal effect on bearing materials like lead indium.

 

[penfold]

What runs on the lead indium? It's a crank or cam shaft made of steel or cast iron, both of which will corrode readily if left in contact with combustion products.

 

[Boater Sam]

What runs on the lead indium? It's a crank or cam shaft made of steel or cast iron, both of which will corrode readily if left in contact with combustion products.

I have never found a corroded crank or cam in an engine unless it has been stripped and left out in the rain for months.
I have dredged engines off river and sea beds with some oil still in them and they have been fine.
Cast iron corrodes far less readily than steel.

 

[vyv_cox]

Are you sure? Is there a good reason why the bearings suffer if filtered old oil passes through them? There will be no metal particles if the filter and possibly a magnet is still collecting them. Carbon from combustion is actually a lubricant. Increased acidity will have a minimal effect on bearing materials like lead indium.

Lead/indium is used only for the overlay, which is microns thick. It is somewhat more resistant to corrosion by weak organic acids, the products of combustion, than pure lead, The bearing material in the vast majority of diesels is a copper/lead mixture, either cast or sintered. However, lead/indium is not a perfect barrier to these acids and being so thin, is readily worn away by combustion particulates in oils that have done excessively long hours without change. Once the overlay has gone the lead is corroded away leaving porous copper, that collapses.

 

[wonkywinch]

Another You Tube favourite of mine, guys who pull cars out of 30+ year storage and fire them up after minimal fettling - https://m.youtube.com/@BudgetBuildz/about

 

[penfold]

I have never found a corroded crank or cam in an engine unless it has been stripped and left out in the rain for months.
I have dredged engines off river and sea beds with some oil still in them and they have been fine.
Cast iron corrodes far less readily than steel.

The innards of an old engine that's been stored with old oil in earlier;

 

[Halo]

That’s an interesting academic question. Change oil and run it hard tied up to the shore. If she ok she is ok.

 

[LittleSister]

I see no reason it won't be fine, nor any reason to run it hard.

I imagine you might perhaps have had a very minor increase in wear etc. compared to having changed the oil more often, but given the limIted engine hours, and that its run successfully, it can safely be ignored.

Write a hundred lines - 'I must remember to change the oil annually' - or just go sailing!

 

[Boater Sam]

The innards of an old engine that's been stored with old oil in earlier;

Interesting, thank you. How long was this engine stored without being run?

 

[penfold]

Approximately 20 years.

 

[Boater Sam]

Approximately 20 years.

Interesting that its only cam followers and lobes that are eroded.
I think that there may well be factors affecting the cast steel other than old oil. If the engine was stationary for 20 years there would be no oil on the cam lobes and followers.