The perennial subject of which oil for a 2-stroke Detroit has been discussed at great length here and on other forums. Essentially, if it doesn't say CF-2*, don't use it. Straight 40-weight is needed for normal conditions, but straight 30-weight can be used for sub-freezing conditions and straight 50-weight can be used for very hot conditions. Whatever you use, it must be a straight-weight oil - multigrades are a big no-no in 2-strokes. Try to find the "Detroit Lubricating Oil, Fuel & Filters" manual online and print it out, along with the "MTU Lubricants For Two-Cycle Engines" manual. Tejas has good info on this subject as well. I'm presently using ConocoPhillips 76 T5X, but I've topped it up with some Delo 100; Luvrbus on the BCM forum says that Delvac 1240 lowers oil consumption compared to Delo 100, so that's another good one to use if you can find it.
My HT740 uses Dexron, so I guess your MT will also use it.
Coolant for dry-sleeve engines such as the 71-series is less critical than for wet-sleeve engines like mine, but must still meet Detroit's requirements. I suggest you start googling for the "Detroit Coolant Selections" manual and print it out for future reference.
My Rockwell axle's service manual says that 85W/140 GL5 gear oil is needed, and I also use it for the front hubs' bearings.
Try to find the "Detroit 53, 71 and 92 Series Operator's Guide" - it has lots of useful info in it.
John
* Yes, I know that CF-2 is now obsolete, but so are 2-stroke Detroits! Suitable oils still say CF-2 on them, and that's what you need to know when choosing them. O'Reilly can order Delo 100, but it's cheaper to have your local distributor get larger sizes of it or whatever you want. Just don't buy it at marine suppliers!
