What type of oil?

[markm]

My R-21 has a 20 hp Yanmar. What type of oil (brand and weight) is recommended and what do most of you use. There are so many choices now, including synthetics, I thought I better get some advise.

Thanks

Mark

 

[Nellie Too]

Always check the Manufactors specification for the engine. They typically are an "SAE" specification requirement. Diesel is different from gasoline engine requirements. Also pay attention to the recommended weight which will be "5w-20, 5w-30, 10w-30, 10w-40 or a straight weight etc. The brand of oil makes littly difference because thy all meet the same specs and are interchangable with exception of the weight. Synthetics also are very good and longer lasting but are higher priced not interchangeable with standard oils (this is what I use). This is coming for an old oil salesman from Valvoline (of course my preference).
Bob

 

[K7MXE]

I use Chevron DELO 400 in 15-40 in the motor and DELO 400 30W is in the transmission. Bob Heselberg in Eatonville Wa

 

[Levitation]

Ooooh boy, Mark... This is like discussing religion (or guns)...

Anyway, to add to the scrum, I long ago settled on Rotella-T 15W40 (non synthetic) for my diesel engines (trucks/boats/bulldozers/ backhoes/ antique tractors / etc.)... Change it every spring on the boat (or sooner if you run a zillion hours) and your engine will outlast you... (and will do it also with Delo, or any other quality oil)
Rotella is available everywhere in the USA - auto stores, Wally World, etc.

Now, if you want to be anal and use synthetic Rotella-T 5W40 - go for it... Just don't believe you should run it 2 or 3 times as long before changing... Change it on the same schedule as non synthetic... In either case your grandchildren will still be running that little engine long after you have seen the green flash...

 

[commander bill]

I use Rotella-T 15W40 in all my diesels including my R25 Yanmar engine & Genset. Diesels see greater bearing & crankshaft loads so higher viscosity is normally required than for gas engines. I have been using it for over 20 years in my tractors and road diesels and it has provided excellent service. As stated above more frequent changes on diesels is very important. Blowby will occur on diesels & oil will become contaimated faster than on gas engines. All you have to do is examine the used oil to see this. Also, used oil from a diesel is much more hazardous due to high acid content than used oil from gas engines.