During what season do you change your engine oil?

[cburger]

I know that oil change times are usually based on a number of hours of motor use. Considering there are components as a byproduct of combustion in oil that can cause engine corrosion I have thought that in areas of the world where due to winter layup having older oil laying stagnant on the surfaces it lubricates over the long winter can contribute to this corrosion and that it would always be preferable to make these scheduled oil changes before motor layup?

[letsgetsailing3]

Makes sense, but probably not your biggest worry.

[Dockhead]

Originally Posted by cburger

I know that oil change times are usually based on a number of hours of motor use. Considering there are components as a byproduct of combustion in oil that can cause engine corrosion I have thought that in areas of the world where due to winter layup having older oil laying stagnant on the surfaces it lubricates over the long winter can contribute to this corrosion and that it would always be preferable to make these scheduled oil changes before motor layup?

Oil changes are by time or hours, whatever comes first. I do mine twice a year - once at the beginning of winter, and once again just before my summer cruise in July. Works out to roughly 100 hours per oil change.

[sailorboy1]

I do mine in the Spring now after the boat gets launched. I used to do in the Fall on haul out due to the "clean oil" theory. But in Fall my oil isn't that dirty and has less than 100 hours on it and I feel the oil is going to absorb moisture during the winter and just need to be changed again in the Spring. So I run the engine hard enough to fully heat it in the Fall to get rid of any water that might be it in, then winterize it and wait.

[Mike OReilly]

No matter how many hours I've motored, we change the oil at haul just before winter storage. Reasons are as you state burger. Of course, if I ever put on 100 hours before the season was up, I'd change the oil mid-season, but so far that has never happened with our diesel.

[cburger]

I had always read that it was a by product of hydrogen sulphide that causes the corrosive action with the used oil. Not sure if this is just a diesel thing.

[sailorboy1]

Modern oil has plenty of corrosion protection and if your engine is making so many corrosion by-products you have bigger issues

[hellosailor]

cb, the difference between old 'used' oil and fresh oil is simply the combustion byproducts. Some water (condensate), fuel, oil, coolant, and a variety of acids and other combustion products.

In modern premium oils there are a lot of additives that combine with the combustion products and neutralize them, especially the acids. So with a good oil and low hours? Those contaminants shouldn't be an issue during layup.

The condensate will be the same, new oil or old.

Which leaves...? Throw the dice, I'd be more concerned with using a modern synthetic oil that has good thin-film sheeting properties, to keep an oil film on the metal parts over the longer layup.

I suppose if you really want to know, you could send out a sample for oil analysis to Blackstone, before and after layup, to see what if anything was changing in the oil. For $50, you'd have objectives facts, for your boat, your oil, your conditions.

[cburger]

Originally Posted by hellosailor

cb, the difference between old 'used' oil and fresh oil is simply the combustion byproducts. Some water (condensate), fuel, oil, coolant, and a variety of acids and other combustion products.

In modern premium oils there are a lot of additives that combine with the combustion products and neutralize them, especially the acids. So with a good oil and low hours? Those contaminants shouldn't be an issue during layup.

The condensate will be the same, new oil or old.

Which leaves...? Throw the dice, I'd be more concerned with using a modern synthetic oil that has good thin-film sheeting properties, to keep an oil film on the metal parts over the longer layup.

I suppose if you really want to know, you could send out a sample for oil analysis to Blackstone, before and after layup, to see what if anything was changing in the oil. For $50, you'd have objectives facts, for your boat, your oil, your conditions.

I use the Shell Tellus 15-40 in the old Perky, according to some "So called" experts considered to be a good product, little leery to start synthetic now in a motor that has never used it. Expect the engine will easily out live me. My current use is nowhere near 100hrs.

[a64pilot]

I am a firm believer in Synthetics, having said that I've seen on some older engines that have changes over to synthetics that have begun to leak more oil soon after the change, but not all engines exhibit this. There are many theories.

[forsailbyowner]

I read in the perkins engine manual to change oil at 1000 hrs or 3 months whichever came 1st. 1000hrs really?

[a64pilot]

Seeing as how you would have to run it eleven hours a day every single day for 90 days to get a thousand hours on it, I'd say it's a pretty safe bet that three months will occur first