Chemical weakening for rubbing away

Winter lingers on so if not sleeping with sheep or counting them to sleep,
how about an oil thread? Many things cause faster parts wear, chemistry
and galvanic action are part of them. Carbon dioxide and water make
carbonic acid, a minor metal etcher, but start of meaner cascade given
time and temp. I do not know how important this is to BI, just that it
exists and some advertise features to reduce chemical attack, such as
suck through venting engine breathers, like Bunn's. Here's
interesting article on wear and tear in general to think on riding into sunsets.

http://www.kleenoilindia.com/Oil%20Management.pdf
Corrosive wear This is chemical or galvanic attack, followed by the removal of the reaction products (chemical complexes) by mechanical action (friction). It can be avoided by the use of effective materials, also by the use of neutralizing additives in the oil. Changing the oil in time may also minimize it.

Steve — galvanic corrosion can be destructive. The swinging arm spindles on Ducati bevel singles and twins were renowned for pitting as a result of galvanic action, and was probably not helped by the marginal lubrication of the original design and lack of maintenance. I still have a spindle from a scrap bike which looks like the surface of the moon, but it had probably been lying in a puddle in a farmyard for decades. The worst pitting takes place where the spindle bears against the bronze bushes. The cure seems to be to hard-chrome them and they should last a long time.

Marine craft have sacrificial anodes to defend against galvanic corrosion, as I am sure you know. I don't have a sacrificial anode on my 70s Johnson outboard run in freshwater only and I haven't noticed any significant corrosion to either the external aluminium or the gearbox internals. Then again, I change the underwater unit's oil regularly.

Steve,
There is an old saying in the taxi and trucking industries - if it never cools down it never wears out.

And with the huge mileages that taxis and trucks can clock up, there appears to be much truth in this saying. ?

So breathers are attacking the problem from the wrong direction ??

its was a bit of a revelation how much chemistry could wear engines, from the insides. I'm Fla boat boy so know about sacrificial metals to give up electrons before the propeller or lower cases did. If power to spare, electronic devices now do this by just turning on, one cathode+ on the good stuff, anode- in the water.

We may think its just the stuff above oil level in storage that reacts to air and oxygen but so can the stuff covered in old oil.

Breathers can have 2 effects, one to lower or at least equalize pressure so oil stays in and ring seal better, or two, if designed for it, to draw in air to help flush acid forming vapors outside to dilute the pollution. Just an equalizing one way check valve PCV breather does not flush out corrosive vapors that can condense and react.

Conclusion 1, when in doubt, drain it out, 2. best to put 1st spring's riding oil in before being put up for winter, 3. pay for more of the cheaper oil or pay more for less of the expensive oil.

It was my understanding that all/most of the internal chemical corrosion inside an engine happens in the first minute or 2 after a cold startup.

The cold metal surfaces condense the newly formed acids, which eat a microscopic layer of metal surface. As soon as the metal heats up to working temp, the acids don't condense on the surface, so the attack doesn't occur hot. And the anti-acid additives in the oil kill the acids formed, so once the engine has stopped the acid attack is neutralized. The standard engine breather will breath out the boiled-out acids out of the oil as it warms up too.

So all the extra breathing in the world doesn't make any difference to this process at all ?

And hence the truckers and taxi owners saying "if it never cools down, it never wears out."

Ah Rohan, always a guiding light to me. I think you nailed our current reality, the additive package alkaline buffers neutralize the acids and heat cooks out the moisture then fresh air fills cases on cooling. Water is denser than oil so tends to sink below oil to the metal below. Today I visited a friend who showed off his serious backhoe, started right up on steady idle in upper 30's wet day. We walked away to leave it till fully warmed to shut off.