Oil change - how often?

[temptress]

So I have been changing my engine oil and filter approximately every 100 engine hours for years and years. I have been thinking is this necessary or could we extend the period?

I am aware of the reasons for changing the oil and of the sulphurous and sulphuric acids that can form . Still I've been thinking.
I used to think you could not change you engine oil often enough.

A recent discussion with a car mechanic has got me thinking. Most cars these days have an recommended engine oil change of every 15K miles (some even more). Say the average car runs at an average speed of 60MPH that's an oil change every 260 hours (or greater if the average speed is slower). I don't but this 'boat' engines are used for less time - people use cars the same way in many instances - just popping to local shops and not on long journeys without the manufacturers recommending any change in service routines.

Certainly engines need to be used. If the boat is lightly used and laid up out of season then a change at the end of the year is probably all that is needed. However if the boat is in constant commission and use are we changing our oil too often? What do others think?

 

[maby]

You are probably correct for an engine out of warranty. For one that is still in warranty, I would probably bite the bullet and service to manufacturer's recommendations in order to avoid any difficult questions if it does break down.

 

[duncan99210]

Most car engines are designed with longer service intervals than they used to have: once oil changes were required every 5,000 miles, now the interval is up to 20,000. This is down to the way the engines are put together along with lower fuel consumption all producing less of the nasties to pass into the oil which leads to the need to change it. In addition, the oils specified for car engines have changed, using longer lasting formulations.

Boat engines are, by and large, old technology diesels with the allied problems of large quantities of nasty combustion byproducts which lead to the need for more frequent oil changes. Generally speaking, most engine manufacturers specify ordinary cheap oils for use in their engines (strip away the 'you must use our branded oil' and check the specification of the oil) so the actual cost of changing the oil is not too great. I change filters and oil at about the 100 hour point and it costs me a total of about £20 a time.

 

[Anders_P42]

I'm not sure a comparisons can be drawn between road and marine engines. A diesel car cruising at 60mph will be at 2000rpm and very low load, turbo producing small amount of boost. A boat at cruising speed would be a bit like a car going up a never ending steep hill with much higher engine load and turbo working hard. Car manufacturers would soon revise their service intervals if that was typical use! I take a car on track and the oil gets changes every two track days, the oil is very black after two days because of the hard work it does.

I'm sure someone else can ship in, but that's my 2p's worth.

Anders

 

[ffiill]

100 hours or once a year if you havnt like me made the 100 hours-I do my 20,000 miles car oil change every 6000 or so miles and fuel filters every 10,000.
The filters and oil are so cheap and the task so easy why just not look after the engine as the dirtier the oil the more the wear on an item with ultimately a finite life.

 

[Halo]

This forum seems to have established that we should use basic mineral multigrade oil in boat engines rather than synthetic ones. This means the oil we use is less expensive. For sure engine oil cleanliness is important for engine life so my argument would be that 100 hours is a good change interval.

 

[rosssavage]

My VP manual says 100 hrs or annually, and gives an oil spec. Hence, it's once every 100 hrs or annually, with the oil they spec. This is an old mineral 'cheap' oil, but if that's what they say to use, I'm happy it's up to the job. There are arguments against using modern synthetic oil in old marine diesels, but I can't remember what they are. Just do what the book says and you can't go far wrong.

 

[KellysEye]

>so my argument would be that 100 hours is a good change interval.

Agree, that's what my Volvo engine manual said.

 

[GrahamM376]

100 hours unless we're still out and about and likely to do a few more (maybe 20 or so) hours but, I always change before winter when the boat is used less. Don't want to leave it laid up for long with dirty and acidic oil.

 

[JumbleDuck]

I'm not sure a comparisons can be drawn between road and marine engines. A diesel car cruising at 60mph will be at 2000rpm and very low load, turbo producing small amount of boost. A boat at cruising speed would be a bit like a car going up a never ending steep hill with much higher engine load and turbo working hard.

Although marine engines tend to run flat out, that flat out can be a lot less stressful than in car engines. For example, I have a 293cc diesel engine in my boat which spends most of its working life producing around 7hp, which is 27hp per litre. My car has a 1.9 litre diesel engine rated at 90 hp maximum, but which probably runs at 50 hp or so for most of the time ... which is 26 hp / litre.

 

[temptress]

Interestiug comment here.

I went to a talk on engine oil delivered by one of Castrol's engineers. He was saying that modern oils have also moved on to provide better all round protection and cleaning. He did not seem to think the use profile on a marine engine made much diffreance nor the age of the engine. although he aghreed that you could not change the oil too often. So i am still wouldering weather 100hrs use/per change is right.

Having sail that I continue to do a change every 100hrs or as clost to this as i can find somewhere to dispose the used engine oil - which can be an issue sometimes.

 

[lotusman]

any comment on changing oil based on fuel used rather than hours run, eg change oil after 200 litres of fuel used?

 

[davidej]

any comment on changing oil based on fuel used rather than hours run, eg change oil after 200 litres of fuel used?

That doesn't seem to make sense - a 10hp single cylinder might do 1litre per hour so it would be 200 hrs while a large mobo might do 200 litres in an afternoon

 

[ianfr]

My VP manual says 100 hrs or annually, and gives an oil spec. Hence, it's once every 100 hrs or annually, with the oil they spec. This is an old mineral 'cheap' oil, but if that's what they say to use, I'm happy it's up to the job. There are arguments against using modern synthetic oil in old marine diesels, but I can't remember what they are. Just do what the book says and you can't go far wrong.

+1 Compared with an engine replacement £20 - £30 per year is nothing.

Ian

 

[Vara]

any comment on changing oil based on fuel used rather than hours run, eg change oil after 200 litres of fuel used?

I asked this question regarding the fuel filters and was given the usual 50/50 advice.

Now I change oil, oil and fuel filters once a year, usually in November, may not be strictly necessary but it doesn't do any harm and only costs about £25.

 

[lotusman]

That doesn't seem to make sense - a 10hp single cylinder might do 1litre per hour so it would be 200 hrs while a large mobo might do 200 litres in an afternoon

sorry, I should have been more specific, the fuel volume needs to be related to the boat, mine does about 1.9 litres/hr hence suggested interval 200litres

 

[lw395]

It comes down to oil is a lot cheaper than engine parts, even if you use the most expensive oil you can find.
In the scheme of things, if you keep the boat say 10 years, and change the oil and filter say twice a year instead of once, that will have cost you about £200?
If that makes the difference of selling the boat with a sweet running engine, it's a bargain.
Even if it only stacks the odds in your favour a bit, it still pays.

 

[temptress]

It comes down to oil is a lot cheaper than engine parts, even if you use the most expensive oil you can find.
In the scheme of things, if you keep the boat say 10 years, and change the oil and filter say twice a year instead of once, that will have cost you about £200?
If that makes the difference of selling the boat with a sweet running engine, it's a bargain.
Even if it only stacks the odds in your favour a bit, it still pays.

I am not thinking about cost just weather it is actually needed. As a liveaboard on the move or at anchor I often find it difficult to find somewhere to dispose of my used engine oil and sometimes have to carry it around wiht me for a long time. Hence the musings as to weather we do in fact change our oil more often than required.

 

[vyv_cox]

Modern synthetic automotive engine oils include complex and sometimes very expensive additive packages that are added primarily to extend oil change intervals and to improve fuel economy. The oil for my car, well under 5 litres capacity, costs £67 for the extra long life type, reflecting the technology that it includes. Simple yacht auxiliary diesel engines need none of this technology, allowing the use of far cheaper lubricants, but this saving does come at a cost, which is more frequent changes and maybe slightly higher consumption.

 

[temptress]

Modern synthetic automotive engine oils include complex and sometimes very expensive additive packages that are added primarily to extend oil change intervals and to improve fuel economy. The oil for my car, well under 5 litres capacity, costs £67 for the extra long life type, reflecting the technology that it includes. Simple yacht auxiliary diesel engines need none of this technology, allowing the use of far cheaper lubricants, but this saving does come at a cost, which is more frequent changes and maybe slightly higher consumption.

Vyv - agree wiht that but therre are cheaper semi synthetic as well as additives in mineral oils these days. What I trying to work out s though do we realy need to change our poil every 100 hours or woul 150 or even 200 be fine. My engine is 21 years old wihyt over 4k houirs and running fine. so perhaps i will just stick to the 100hrs oil changes.