This is an area where you may get a different answer from Newell than from Detroit Diesel. Detroit Diesel says do not run ANYTHING but 40 wt oil that meets specific requirements in their two stroke engines except under very specific circumstances:
The lubricating oil requirements for On-Highway applications of Series 53, Series 71, and Series 92 two-stoke engines are outlined in this section.
See Figure 2-2 for the API Symbol of two-stroke cycle engine oils.
API SERVICE CF-2 SAE 40
Figure 2
Lubricating oil for On-Highway applications for two-stroke cycle engines must meet the following requirements:
□ 1.0% Ash Maximum as measured by ASTM D874
□ 7.0 TBN minimum as measured by ASTM D2896
□ 700 ppm zinc minimum as measured by ASTM D5185
At ambient temperatures below freezing (0°C [32°F]), sufficient starter cranking speed may not be achieved to start the engine with SAE 40 grade oils. Where starting aids are not available or at very cold temperatures (-18 to -32°C [0 to -25°F]) even if starting aids are available, the use of multigrade SAE 15W-40 or monograde lubricant SAE 30 will improve startability. These lubricants must possess a HT/HS Viscosity (measured by ASTM D 4741 or equivalent) of 3.7 cP minimum. These oils must be replaced with monograde SAE 40 lubricants as soon as ambient conditions permit.
7SE270 Copyright © 2007 DETROIT DIESEL CORPORATION
Here is the link to download this entire booklet
http://www.detroitdiesel.com/support...270_010307.pdf
There is lot's of additional information in this document and it makes good reading.
Newell has recommended Mobil Delvac 1 synthetic 15w-40 diesel oil even in the two-stoke Detroits.
I recently had to have a gasket replaced between the block and the blower in my 8V92. One of the first questions Stewart & Stevenson Detroit Diesel ask was "You are running straight 40 wt oil aren't you?".
As far as Amsoil, the Detroit Diesel booklet above does include Amsoil PCO 15-40 as an acceptable oil for the Series 60.
While I run 40 weight oil, if I were to use anything else I would probably go with Newell's recommendation.
I monitor the Detroit Diesel Two-Stroke forum, as well as the Wanderlodge forum (which has a large number of members that are running 8V92's), and both recommend staying with 40 wt oil that meets Detroit Diesel requirements even if you have to order it since even a few Detroit Diesel service centers aren't carrying it in stock on a routine basis. But they can typically get it in a few days.
Hopefully Newell will provide additional input on this issue as it relates to the two-stroke Detroit Diesels.