Detroit Diesel 6-71

In cool waters your looking for a CF-2, 30W.
In warmer waters go to a CF-2, 40W.
Shell Rotella, NAPA, Mobil and others sell this stuff.

Your looking for that API badge of CF-2.

If your not sure what I'm typing about on CF-2, please type back.

6-71N, 6-71T, 6-71TI or 6-71TIB (no oil will save that last one)

6-71 Turbo, Inter-cooled, By-pass blower?
My favorite..
Massive crank bearing between each massive rod/piston throw. I have witnessed 600+ reliable HP from that block.
3K RPM not a problem to 700+ HP.
Like an outboard engine, the straight 6-71 was never pushed.
I always dreamed of an inter block (between the block inlet and blower) air cooler to make a 6-71 TIAB.
Sad that Penski did not push the 6-71TIB (6-71TIAB) on DDEC.

Welcome to YF.
I run CF-2, thru my veins. Always tap on YF for DDC questions.
Tell us more about your ship and power.
Our members are world wide and always have ideas to help. Sometimes we get carried aweigh but we are here to help.
☺☺

Low ash is required. Very important.

"For two-stroke cycle engines, Detroit Diesel recommends lubricants with a sulfated ash content of 1.0% or less"

Your zip is Maryland. Where does your boat operate and what seasons?
Block heaters?
Fresh or lots of hours on the mains?

Low ash is usually covered in CF-2.
Some brands more/less than others but the TIB change interval covers any slack in the specs.

Oil lab reports is always the best answer to any concern or quality issues.
I trust the OP knows this. If not, reminder; send your oil samples out to a lab often.

I'm assuming TD 506 clutches. Yes, same oil as mains.
With block heaters, stay all with CF-2, 40W.
No block heaters, CF-2, 30W when water temp lower than 70°f.

Yep, That's where we are at.
NAPA Fleet 75-118 & Shell Rotella T1/40 are your best bets for engine and clutch. I recall Mobil 1640 is good also.

<--- Currently on The St Johns river south of Jacksonville FL.