Oil - to change or not to change?

[Heckler]

I think it's a valid question.
Like most of us I have the oil changed annually.
It's prudent but is it necessary?

YES
change the oil regularly, the reason it gets black is because it collects by products of combustion and keeps them in suspension, the bits are too small to be captured by the filter. The oil gets thicker over time as it gets loaded with bits and as the oil degrades.
Change it, regularly!!
Cheapest maintenance you will ever do! By the way Tesco/Asda finest is more than good enough for our relatively crude marine diesels!
Stu

 

[Heckler]

What a heap of udatabased gobledygook.

Modern Mid Range high speed diesel engines are approved for UP TO 40,00 km or 500 hr oil drain intervals depending on duty cycle. Take note of Tinkickers comments and ignore them at your perill. Bus companies are noted for wrecking darn good high speed diesel engines long before their B50 life because of their obsession with leaving lube in for well over 1,500 hours or two years.

I would certainly never describe little light duty industrial puddle jumper engines such as Kubota and Yanmar as archaic technology and where does this nonsense come from that they run cold come from....They have properly designed thermostatically controlled cooling systems giving then sensible cost effective 200 hr lube oil drains.

Posters who talk about leaving lube in, are nearly as bad as UK bus companies. Leave lube in for too long and engine WILL develop appitite for oil, top up the lube and you top up the additive pack, oil lasts a little longer but appitite increases therefore increasing top ups and QED the the additive pack. Advocates of long drain lube intervals never make accurate measurements of lube oil consumption, saving with one hand giving away with the other.

Commercial vehicle/agriculturalt parts distributors as well fuel distributors tend to offer best pricing. Also sticking to correct spec is vital. Talk of straight weight 30 lubes is simply nuts unless you run a mechanical CAT 3116/3126............Vintage tractor guys are generally bunch of know nothing numpties.

Why are you continually talking gobbeldy gook? Bus engines, rail engines? WTF have they to do with yacht engines? B50? duty cycle? uhhhh? puddle jumper? additive pack? duhhh!
If you think that using technical language in a non grammatical way gives you credence, think on!
Stu

 

[Bobobolinsky]

How else would you get the oil out of a yanmar 2gm20 with no sump plug?

Turn it upside dowm

 

[Daydream believer]

Deleted

 

[sailorman]

Hey guys i detect a hint of animosity here
It does not matter what we say in this thread those that want to change oil will . Those that do not want to won't. A simple exchange of views is ok but if spmeone disagrees then to each his own.

Oh dont go & spoil it with sensible suggestions

 

[Daydream believer]

Oh dont go & spoil it with sensible suggestions

Wow there must be loads of people trawlling this thread. I only entered it then changed my mind & deleted it. Yet it was picked up in seconds

 

[Latestarter1]

Why are you continually talking gobbeldy gook? Bus engines, rail engines? WTF have they to do with yacht engines? B50? duty cycle? uhhhh? puddle jumper? additive pack? duhhh!
If you think that using technical language in a non grammatical way gives you credence, think on!
Stu

The basic rules stay the same regardless of engine size, since when was Practical Boat Owner become the sole provence of yacht owners.

Yes I have owned a Sadler, Nauticat and offshore power boat around the same time, enjoyed them all. However when it comes to wee yacht motors the guys that use them immerse themselves in their own perverse and often out-dated and un-databased little world.

Just stick to contributors dripping on about irrelavant and worthless mainly automotive stuff if it makes you real happy.

Read it or not, choice entirely is yours..

 

[Colvic Watson]

This question has been done to death in this forum, there is a page on it in my website, Engines>Oil for yacht engines.

Virtually every club, society, etc that runs old engines in cars, boats, tractors, etc agree that using modern high performance oils in them will accelerate their demise. For example, many canal boats use BMC 2.2 and 2.5 litre engines. Morris Lubricants make API CC oil, a grade that became obsolete in the 1950s, specifically for them and sell a lot.

Hi Vyv and others. I read your site on engine oil and in my ignorance couldn't decide what grade of oil for a late 1970's Thornycroft 230? I know not to go synthetic but could you or someone else spell it out for me!

Thanks.

 

[sailorman]

Hi Vyv and others. I read your site on engine oil and in my ignorance couldn't decide what grade of oil for a late 1970's Thornycroft 230? I know not to go synthetic but could you or someone else spell it out for me!

Thanks.

SAE 15>40 CF or CF4 from local SM

 

[Spyro]

Turn it upside dowm

Why didn't I think of that

 

[grumpygit]

I have read posts from Marsupial and grumpygit and whilst some of their logic is nuts I kind of agree with their sentiments.

Having actually designed diesel engines and formulated their operating peramiters, and represented UK members of ACEA against excesses of EU I cannot believe people make such hard work of maintaining marine diesel engines. Other posters waffling and making constant references to boutique automotive diesel engines which employ all manner of after treatment strategies of zero relevance to marine duty cycles and emissions. Talk of engines grinding with metal to metal contact, lube filters being referred as merely rock stoppers, this is all simply vapourware.

#1 No manufacturer is prepared to compromise engine life, just the opposite there is constant pressure to increase B50 and B100 (Industry durability/reliability standards).

#2 RTFM it is the Bible, not another owners opinions.

#3 Having read the manual just understand how lube oils work. Clean and fresh 15W40 lube to say ACEA E5/7 will have TBN (Total Base Number) of around 10. and TAN (Total Acid Number of 0. Combustion formas acids which gradually degrade the TBN. When TAN exceeds TBN lube has had it! The clever bit is to predict (dependant on duty cycle) the point at which the two graphs cross over. TBN depletion is a pretty linear curve whilst TAN is a scatter graph. Oil sampling which includes TBN Vs TAN result is expensive and often cheaper to simply change the lube oil. Also remember that topping up lube tops up the TBN, therefore lube will appear to last longer in an engine which has a 'drink' problem.

#4 Extended life filters are dangerous as they can actually damage the vital additive pack. Correct spec filters are not 'rock stoppers' they are critical components in the system.

Trust me when you are putting a contract spec together for horizontal 19 liter rail engine life to overhaul is your call, the operator only pays you for productive 'up time'. Rail engine duty cycles are evil, diesel engines love constant speed, they rarely see that in a DMU. Operator pays you for say 15/17,000 hours of productive time to overhaul. Lube service intervals are your call, too short and you do not get the contract, too long and engine fails to meet contract requirement and you lose your job. Understanding non linear TBN depletion is critical.

How do we get around all this horse manure in boats? We just change frequently, not forgetting the filter!

NUTS!! I'm so pleased I've been certified by such an expert. Well, I'll go see if I can find Marsupial back at the asylum . . . .

----------------------

 

[tinkicker0]

That's interesting. Roughly when was the changeover? I mean, are we talking "pre-war" or last 20 years or...? Mine's a bit of an oddball - no filter, no oil pump, roller bearing crank (but plain bearing big end). I've nearly always just use a plain mineral diesel multigrade - tried that Castrol Magnatec semit-synthetic once though.

No changeover as such. A rule of thumb is that if your motor does not have an external easy replaceable spin on or cartridge filter, then you need to be finding out exactly what additives in the oil your engine needs.
As others have said...RTFM.

Think of a small petrol generator or small industrial motor. They do not have replaceable oil filters and one would expect them to require a low dispersant oil. However they often spec modern high dispersant oil for use in them.
This would seem to be the opposite of what I have previously said, however the drain times would be in the region of 15 _ 20 hours, the oil would hardly be discoloured in this time.

This is why you should always do your homework when choosing oil. Asda or other generic oil may not be good for your motor. On the other hand....you may get lucky.

 

[sailorman]

No changeover as such. A rule of thumb is that if your motor does not have an external easy replaceable spin on or cartridge filter, then you need to be finding out exactly what additives in the oil your engine needs.
As others have said...RTFM.

Think of a small petrol generator or small industrial motor. They do not have replaceable oil filters and one would expect them to require a low dispersant oil. However they often spec modern high dispersant oil for use in them.
This would seem to be the opposite of what I have previously said, however the drain times would be in the region of 15 _ 20 hours, the oil would hardly be discoloured in this time.

This is why you should always do your homework when choosing oil. Asda or other generic oil may not be good for your motor. On the other hand....you may get lucky.

My Briggs lawnmower has semi synthetic 10>30.
when i bought it at some 30 yrs old it developed valve problems. serviced the cylinder head, then a damn valve collet ( key hole type ) dropped out. so head off again.
i then looked on the B & G site & saw that i should be using a thinner oil & i think that was the cause of the original valve problem, lack of lube to the exhaust valve stem. this being a splash lube side valve engine

 

[tinkicker0]

Why are you continually talking gobbeldy gook? Bus engines, rail engines? WTF have they to do with yacht engines? B50? duty cycle? uhhhh? puddle jumper? additive pack? duhhh!
If you think that using technical language in a non grammatical way gives you credence, think on!
Stu

OP never mentioned yacht engines to be fair and LS has credence in spades. Why the animosity?

 

[Robert Wilson]

OP never mentioned yacht engines to be fair and LS has credence in spades. Why the animosity?

Thank you for pointing that out!!

However, I have found the whole site fascinating and "almost" helpful regarding my boat engine. Kubota 13HP, of indeterminatable age.

I have to admit that the scientific wise-ones have left me far behind.
I have read the manual and hope that it relates to my engine.


Thank you one and all - and I'm sorry I've stirred up a hornet's nest on an old topic!

 

[Avocet]

This question has been done to death in this forum, there is a page on it in my website, Engines>Oil for yacht engines.

Virtually every club, society, etc that runs old engines in cars, boats, tractors, etc agree that using modern high performance oils in them will accelerate their demise. For example, many canal boats use BMC 2.2 and 2.5 litre engines. Morris Lubricants make API CC oil, a grade that became obsolete in the 1950s, specifically for them and sell a lot.

Ok, thanks for that, and I can see some of the arguments you make against synthetic oils, but why stick with a monograde when there's a multigrade available? Multigrades just seem (to me at least) not to have a down-side? The way I see it, our engine was originally specified (in our sort of climate at any rate!) to use a straight 30 grade. If I stick a 10W40 in there, surely a cold 10W40 is not going to be any thicker than a cold straight 30, and yet when hot, although it will be thicker than a hot 30 grade, it won't be thicker than a cold 30 grade, so it should be still well within the range of permitted viscosities? That way, I get easier cold cranking but still get at least the same bearing protection when hot, if not better? (Also, this engine is a bit weird in that it doesn't have an oil pump or a filter. The main bearings are rolling element bearings and the big-end is a traditional shell bearing but with a scoop on the bottom of the conrod that just dips into the sump every revolution and scoops a bit of oil up into the gap between the big end bearing and the crank.)

 

[vyv_cox]

I don't think I advocate a monograde anywhere. I have owned many air-cooled VWs, for which a monograde was originally specified, but I always used multigrades.

I would not use a 10W/40. These low viscosity oils are for one purpose only - fuel economy. 10W is not quite enough for a full hydrodynamic film and an old engine with perhaps some wear, copper-lead bearings and an unhardened crankshaft will not be happy. I would use 15w/40.

 

[Marsupial]

Ok, thanks for that, and I can see some of the arguments you make against synthetic oils, but why stick with a monograde when there's a multigrade available? Multigrades just seem (to me at least) not to have a down-side? The way I see it, our engine was originally specified (in our sort of climate at any rate!) to use a straight 30 grade. If I stick a 10W40 in there, surely a cold 10W40 is not going to be any thicker than a cold straight 30, and yet when hot, although it will be thicker than a hot 30 grade, it won't be thicker than a cold 30 grade, so it should be still well within the range of permitted viscosities? That way, I get easier cold cranking but still get at least the same bearing protection when hot, if not better? (Also, this engine is a bit weird in that it doesn't have an oil pump or a filter. The main bearings are rolling element bearings and the big-end is a traditional shell bearing but with a scoop on the bottom of the conrod that just dips into the sump every revolution and scoops a bit of oil up into the gap between the big end bearing and the crank.)

I will admit I am not an expert on modern oils but I can tell you that your splash lubricated engine will also rely heavily on oil mist to lubricate the other parts, especially the piston and small end. My knowledge of modern engines is that they don't leave anything to chance and everything that was previously oil mist lubricated is now sprayed with oil under positive pressure - to cool as much as lubricate - this is to do with emission requirements as much as anything; internal bits need to run hotter to comply. The modern oils I have seen in action have very different characteristics (suited to modern engines) but don't seem to have the same mist qualities as mineral varieties - just a "casual observation" so I would be wary using these on an old engine for that reason alone.

Have a nice day

 

[Plevier]

Is it worth worrying about the difference between CF and CF-4 (as I can't find CD anywhere)?

Taking a mineral diesel 15-40 in each case
Planet (made by Comma) from my local motor factor is CF
Tesco's is CF-4
Asda's is CF
Halfords claims on the can to meet both CF and CF-4 - how can that be?

(I note Vyv suggests CF-4 as being nearer to the TBN of CD than CF is, but is it critical?)

 

[sailorman]

Is it worth worrying about the difference between CF and CF-4 (as I can't find CD anywhere)?

Taking a mineral diesel 15-40 in each case
Planet (made by Comma) from my local motor factor is CF
Tesco's is CF-4
Asda's is CF
Halfords claims on the can to meet both CF and CF-4 - how can that be?

(I note Vyv suggests CF-4 as being nearer to the TBN of CD than CF is, but is it critical?)

if the oil meets CF-4 it will meet CF as it encompasses that grade as it does,CC,CD specs