Change Oil and Filters Beginning or End of Season

[Chotu]

i followed Gord’s plan exactly. Even the spring part.

Now, i don’t store the boat anymore so it’s a different situation. Outboard impellers in ice is my main quandary these days. When the cooling system is a block of ice and you still need to use it. Maybe i’ll start a thread on that

[Mike OReilly]

While I'm sure there's something to the whole 'not wanting old oil sitting over winter' thing, I think the real reason I usually do it at haul-out is because that's the way I was taught by fellow owners when I first go into big-boat ownership.

I really doubt that it makes a substantive difference for most cruisers.

[sv_pelagia]

Here in British Columbia, we use our boat yearround. There is no "end of season").



(Admittedly, we use boat much less October - April.)

[Kd9truck]

Yanmar says 200 hrs so that’s when I change it, beginning of season middle or end of season. My 4 cylinder motor has 4K hrs and the oil after 200hrs is still very clean.

Cheers

[NBs]

Hi

Of course, once the season is over, there is no reason to postpone oil maintenance until spring. It's not a matter of faith that if the tbn has worn off after you've run the engine for a good few hours, the oil will be acidic and make pitting corrosion. Of course, if I've used the engine for 30 hours or so, it's all the same... The engine is expensive to overhaul and oil changes cost the same whether you do it at the end or beginning of the season, so there is no rational reason not to do it in the fall. Just my opinion and that of the engine manufacturer 😊

[paul2884]

We do it at the end of the season, like to leave the engine with nice fresh oil when not in use.

[FPNC]

At the end of the season.

There are two things you don't want to sit in your engine block for 5 months. Dirty oil and moisture.

Run your engine for about 40 minutes under load. Get the engine as hot as you should within in the normal operating range. This helps dry out any moisture in the block. Then change the oil and filter.

[Schono]

I recently attended a diesel engine maintenance seminar by Nigel Calder. He made a case that it doesn’t really matter anymore whether you change the oil pre-layup or after. In the past, the advice was to change it at the end of the season so that the acids in the used oil wouldn’t be sitting in the engine. However, they were primarily sulfuric acid that came from the sulfur in the diesel. Now that we have low sulfur diesel, that is no longer an issue. His advice - which I agree with - is still to do the maintenance - change the oil, oil filters, fuel filters, etc - in the fall but with the rationale that it gets it out of the way and you won’t have to worry about it at the start of the next season.

[Mike OReilly]

Doesn't all the oil drain down into the bottom oil pan over a months-long layup? If so, what difference does it make if the oil is somewhat acidified?

I almost always change my oil at the end of the season, just before hauling out. This is how I was taught, and it is the most convenient approach for me. But given the very low number of hours I put on my engine in a typical season (<30 hrs), I really doubt it makes very much difference.

[FPNC]

Originally Posted by Mike OReilly

Doesn't all the oil drain down into the bottom oil pan over a months-long layup?

No. It does not. It sits in the bearings and journals and oil pump and oil passages and oil filter. The sediment in that oil settles out. Then in the spring, you start the engine and pump that sediment through the bearings.

I'm not even sure why this is a topic. It only makes sense to change oil prior to a layup.

[Colin Stone]

I get my oil analysed each November. The current oil is now 721 hours old and I've just drawn the sample for this year. Last Nov after 456 hours the TBN was 10.1 mgKOH/gm, down from new oil 11.0. TAN was 0.67 mgKOH/gm. Oil needs changing when TAN and TBN cross on a graph - ie both at approx 5.
I'm using HVO 100 drop in diesel replacement. No sulphur at all, so virtually no acidic combustion products. Plus cleaner smoother running and a bit more power. Also immune to bugs and really long tank life - 15 years.

[Mike OReilly]

Originally Posted by FPNC

No. It does not. It sits in the bearings and journals and oil pump and oil passages and oil filter. The sediment in that oil settles out. Then in the spring, you start the engine and pump that sediment through the bearings.

I'm not even sure why this is a topic. It only makes sense to change oil prior to a layup.

OK, good thought. So how long does it take to get enough sediment that this has a measurable impact? Depends on the engine, I assume. But if you're generating that much debris in the oil in such a short span of time, don't you already have bigger engine problems?

Has this 'common sense' been tested? Anyone aware of any actual research or experiment to show the difference? One way could be to find a location where the common practice is to change their oil at the beginning of the season. Then, look at the rate of oil-related engine issues.

As I say, I almost always change the oil at the end of the season. But I remain skeptical that it really makes an actual difference for most seasonal cruisers.

[JBsurfin]

Originally Posted by cburger

Would like members opinion on if its best to change my boats oil and fuel filters at the end of the season or in the spring at the beginning of the season?

I do it at the end for the sake that its one less thing I have to think about during spring commissioning. Boating here in NJ is basically over by Nov, so I have time to do it before final lay up.

[Bill_Giles]

Our 23-year old engine gets fresh oil every 100 hours and filters every 200. It does not matter the season. However, come end of the sailing season at say 95 hours we do a change although the boat continues on short trips through the oct-Mar months.

[ranger58sb]

Previous engines, normal oil, easy quantities, only one filter each engine, similar maker's recommendations, I changed once/year.

Now we have larger, high-performance engines. Our manufacturer-specified oil change intervals are every 400 hours, or "at the latest, once per year." Full synthetic oil (and only from among the few on the maker's endorsed list). That of course especially would have applied during the original warranty period.

Now with approx 18-gallons of synthetic (usually Rotella T6) required for each change, and two filters each engine, I've begun changing oil when (Blackstone) sampling analysis suggests I should -- and TBN is low, etc.

Our first analysis at 127 hours, 1 year 4 months including our delivery from Ft. Myers to Annapolis, suggested 200 is OK. Recent analysis at 225 hours (1 year 3 months including a winter trip to Charleston and back) suggests 300 is OK for next time. Analysis isn't pointing out any abnormal levels based on time intervals.

Some of my plan is about managing cost of supplies. Some is about managing my labor time (and there's some significant schlepping involved).

-Chris