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marth · 22-10-2020, 10:48

I was just wondering what you guys use in the old diesel engines? I've got a Yanmar 8hp from 1979. I was checking the prices and the inboard mineral oil started from 40eur/5l whereas regular mineral oil 15w40 was 12eur.

Asked my mechanic, he basically told me the price difference is the boat picture on the can. Asked the guy from the lubricant shop who couldn't think of a reason to go with this more expensive one (it was an automotive store).

Is there really a difference?

sailormed · 22-10-2020, 11:26

Having an old engine that has been running for years with "old" oil without additifs, I would continu using the "old" oil. Don’t scare your engine by changing his diet. You do the same with old people, they have their habits, let them keep those habits, they will live longer and happier

Emmalina · 22-10-2020, 11:26

LOL what the hell is marine grade ???? I use Castrol CRB designed for "mature " engines and it works fine..

marth · 22-10-2020, 11:45

Quote:

Originally Posted by sailormed

Having an old engine that has been running for years with "old" oil without additifs, I would continu using the "old" oil. Don’t scare your engine by changing his diet. You do the same with old people, they have their habits, let them keep those habits, they will live longer and happier

good point. I had the reverse case actually. The previous owner used expensive inboard oil and I went with the regular one.

Shrew · 22-10-2020, 11:53

TMK there is no such thing as "Marine Grade Oil". Oil is based on the API Service Category and the SAE Grade (weight).

Every engine manufacturer that I know of publishes these specs in their manual.

API Oil Categories:

https://www.api.org/products-and-ser...l-c-categories

All API grades are backward compatible. This means you should be able to use any API rating that is equal too, or higher than that recommended by the manufacturer.

Note that the API rating for Diesel is different than Gas, even for oil that is the same weight. So not all oil of the same weight is necessarily the same.

SAE Oil Grades:

https://www.lubricants.total.com/what-are-oil-grades

I use Rotella oil in my engine, transmission and generator. As long as both the API and weight is correct, then you should be fine.

Tayana42 · 22-10-2020, 13:34

My Yanmar 4JHE is from 1989 but a bit bigger than yours at 44hp. I use Delo400 LE 15w40 non detergent oil 6qts.

mjscottinnc · 22-10-2020, 13:43

Stepping outside of the manufacturer’s recommendation caused me to start burning oil, went back to strength SAE 30 weight, she purrs like a new born. Using ‘better’ products isn’t always better.

B_Hunter45 · 22-10-2020, 13:45

Engine oils are the same, gear oils are different, the marine oil will remain an 'oil' and not emulsify even if water are added to the oil. I used amsoil on my power cruiser years ago and this fixed gear oil leakage.

dennismenace111 · 23-10-2020, 09:35

No one uses Shell Rotella T4? It seems to work great for my 1987 2GM20F.

Paul Kelly · 23-10-2020, 09:43

As many Marine Diesel engines, especially the smaller ones, are based on Tractor engines, I've just bought 20 litres of Tractor oil which is about half the price of branded motor oil, marine or not.

Scubaseas · 23-10-2020, 10:01

Quote:

Originally Posted by marth

I was just wondering what you guys use in the old diesel engines? I've got a Yanmar 8hp from 1979. I was checking the prices and the inboard mineral oil started from 40eur/5l whereas regular mineral oil 15w40 was 12eur.

Asked my mechanic, he basically told me the price difference is the boat picture on the can. Asked the guy from the lubricant shop who couldn't think of a reason to go with this more expensive one (it was an automotive store).

Is there really a difference?

Your mechanic is right. Use any ACEA oil rated for diesel use. Rimula (any) would work fine. Synthetic works better than mineral but either will work just fine in motors new or old.

thinwater · 23-10-2020, 10:06

For gasoline engines there is TC-W and FC-W. The difference is corrosion protection. But diesel is different.

Cheechako · 23-10-2020, 10:51

Quote:

Originally Posted by Tayana42

My Yanmar 4JHE is from 1989 but a bit bigger than yours at 44hp. I use Delo400 LE 15w40 non detergent oil 6qts.

Delo 400 is so called "detergent" oil from everything I've seen.

As someone who took apart many engines in the "old days" when detergent wasn't common, trust me, you dont want non detergent generally. The difference in an engine after even 60k miles with detergent oil and one with non detergent is about an eighth inch of black sludge built up throughout the engine internal surfaces.

However I do agree, if you have an engine that has always had non detergent, I probably wouldn't use detergent thinking that it will start to dissolve that debris and run it through the engine bearing surfaces etc.