What oil do you use in your diesel?

[canavap]

I changed my oil in the fall as I was supposed to do but now I am perplexed by my choice of oil. My Universal manual (M-25XP) says to use SAE 30 or 10W40 oil. However, many that I talk to say to use 15W40 oil with marine diesels.

Fellow C30 owners - what type of oil do you use? Also are there specific brands you use and are they really that different?

I put less than 50 hours on my engine a year so there is not a lot of wear and tear. But I want to treat it right and keep it for the foreseeable future.

Much thanks for your insight.

 

[Don S/V ILLusion]

This is more a function of what engine you have rather than what boat it is sitting in. Just a suggestion but - You might get a broader response if you expand your query beyond c30 owners.

My only insight into the more important issue is that your engine mfg might be a more authoritative source of info than any other.

Personal opinion - as long as it is diesel rated oil, I doubt it makes too much difference.

 

[Bad Obsession]

I use 15W40 in my boat engine and in the engine of my Ford F-350 7.3 liter diesel. That is what is best for diesel engines.

 

[txtowman]

I used to work for a very big oil company, in a construction division.
At all times we were guinea pigs for different oils.

They decided through all the research that 15/40 was the best for all the engines they run. gas diesel briggs, kohler and the really big cats and murphys.

I don't expect anyone to accept this as the gospel, but I comvinced a company that I later worked for to switch, they haven't blown a motor since. that was 1988.

I run delo 400 15/40 in everything.

 

[Stu Jackson]

We have an M25 engine, too. I've used every different type of oil, and both synthetic and regular. I have found NO difference.

 

[Bob S]

I use Shell Rotella 30W but as Don and Stu suggested, any diesel rated oil will work. It's more an issue of how frequently you change it. Every 50 hrs is about what I do.