Md7a oil?

stu9000

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Having read martyng's post on oil I am wondering what type of oil I should be buying for my aged but historically well looked after MD7a engine. I had her looked over when I bought the boat and the engineer was v complimentary. So I need to do it right and maintain that treasured reliability.

Having read around I still an wondering

- what oil should I buy?

- can I use the same oil in the engine, sail drive leg and reverse gear?

- where should I get oil filters? Surely own brand type is OK.

She is a dry boat.I imagine I'll do about 50 running hours over the season (fairly wild guess).

Thanks all

S
 

Minchsailor

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I had one of these in my last boat. You don't want an oil that is too good. These engines are very robust, low stressed massive bearings with quite generous clearances compared to more modern types. Any generic 20/40 or 20/50 should be OK. Can't speak for the saildrive.
 

Topcat47

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Do NOT use synthetic or semi-synthetic oils. You can get older spec lubricants from agriculture; engineers but a CD spec 20-50 mineral oil will do fine.
 

Jokani

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This is what was recommended to me by a Marine Engineer to use in my MD2B, which agrees with the above advice, I also used the same oil in the gearbox.

comma-classic.jpg
 

bedouin

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Until recently I had an MD2B - that really didn't like multigrade. I switched to SAE30 and it worked fine.

The problem I had was that the oil pump would not prime (reliably) with the lighter oil. I suspect I was trying 10-40 and it may be that 20-50 could work - provided the oil pump primes it won't do any harm,
 

VicS

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This is what was recommended to me by a Marine Engineer to use in my MD2B, which agrees with the above advice, I also used the same oil in the gearbox.

1646.jpg

I guess he doesn't like your engine very much....

That is a non detergent oil to only API spec SA. It is suitable only for vintage petrol engines and even then requires very frequent oil changes.

I'd definitely suggest looking for a different Marine engineer
 

Jokani

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Sorry for the bum steer on the Comma, and thank you for putting me straight Vic.

It's one of the reasons I like this forum so much, it's gives protection from people (like me) who think they know something.

Enjoy the rest of the weekend all.
 

stu9000

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Stu:
this web page, written by a regular forumite, has lots of good information on oils for yacht engines: https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx

Vyv's a pretty modest chap on here, but if you read his brief biog on the 'About Us' page of his website, you'll get a sense of the authority with which he writes.

A well written and informative link. Thanks.

So, if I have this right, I want a mineral oil with a TBN of 4. API CD.

I understand this can be hard to find?
 

Tranona

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A well written and informative link. Thanks.

So, if I have this right, I want a mineral oil with a TBN of 4. API CD.

I understand this can be hard to find?

CE and CF are easy to find. This is the spec of basic diesel oils sold in supermarkets and will be fine in your engine.
 

macd

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A well written and informative link. Thanks.

So, if I have this right, I want a mineral oil with a TBN of 4. API CD.

I understand this can be hard to find?

Yes, CD is evidently hard, but by no means impossible, to get hold of. (It's a while since I've shopped for oil in the UK.) This thread might trigger some sourcing suggestions. (Edit: there you go, Tranona's already on it...)
Vyv has often written that CF-4 is an acceptable substitute, and does on the page you read. He might be along in a while to amplify.
 

VicS

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CE and CF are easy to find. This is the spec of basic diesel oils sold in supermarkets and will be fine in your engine.

But is it not the high TBNs of oils of these API specs that Vyv objects to ? Or rather the effects of the additives giving the high TBNs on older engines
 

stu9000

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But is it not the high TBNs of oils of these API specs that Vyv objects to ? Or rather the effects of the additives giving the high TBNs on older engines


Indeed.

"the TBN of API CD is 4, of API CE it is 10.5 and for API CF it is 16."

"There is a great deal of evidence to show that use of an oil with a TBN that is too high for the duty can lead to several problems, particularly high wear rates of cylinder bores"

Quotes from
https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx

Ill have look round. Can't be that hard to find surely

S
 

vyv_cox

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For your engine I would buy API CC from Morris Lubricants. http://www.morrislubricants.co.uk/ They don't make API CD but there is little difference between the two. I use their API CC 20/50 in my BMC 2.2 diesel, as do hundreds of canal boat users, their main market.

I would definitely not use a 10W-40 viscosity oil in an older boat engine. The only purpose of these low viscosity oils is fuel economy in car engines designed to take them, with hardened crankshafts and aluminium bearings. Older yacht engines have no need for the fuel economy and will suffer increased bearing wear and maybe worse using thin oils.
 

bedouin

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Yes, CD is evidently hard, but by no means impossible, to get hold of. (It's a while since I've shopped for oil in the UK.) This thread might trigger some sourcing suggestions. (Edit: there you go, Tranona's already on it...)
Vyv has often written that CF-4 is an acceptable substitute, and does on the page you read. He might be along in a while to amplify.
In fact our local car shop stocks this (only hold a couple of cans though) - apparently it is still commonly used in agricultural machinery.
 
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