Detroit Diesel 6-71

MANN also makes good filters, but for the little price difference I stick to dealer filters.

My Viking 44 motor yacht has been running it’s DD 6-71TIBs since at least 2000 on Rotella T1 40w
The oil is changed every year except on a year I hardly used the boat. 5 hrs. I just don’t run them on the pins. Have owned her for 6 years and previous owner had her since 200o. Same guys have taken care of her since PO purchased
Starts right away and smokes for just a few seconds. No major problems. I boat in northern lower Michigan. Only use the black heaters in early spring.

Update;
Was just working with my vendor on another Delvac 40 order.
Discovered I typed wrong on this and another post.
Mobil 1640 is CF rated.
Still, 1240 is CF-2 rated.

Bottom line, if using Mobil products, use the 1230 or 1240 for Detroit two stroke engines.

I am sorry for my bad data on earlier post.

Last order July 2023. Another 10, 5-gal pails coming in.

Delo 100 40w is what I use.
I haven't had any problem finding it.
I think my motors like it!

Yep, Delo 100 is CF-2 rated.
Like my post #2, I have used many oils for my customers. At those times, Chevron Delo 100 just did not offer any discounts.
Now that we have closed shop, I shop just for our Bertram.
This year, our Mobil distributor in Jax came thru again. Their truck should be dropping on us next week.

The specs on the Mobil 1640 are good!, and the price is reasonable. Thanks for the info.
I always used Delvac 15w40 in my Cat motors (purchased from walmart $) and it performed as well as the CAT brand oil.
I never knew that Mobil made CF 2 oil.
I learned something today!
thanks.

Please re-read post #24.
For Detroits you want Mobil Delvac 1240, Not 1640.