Correct fluids for Crown Bus.

[GWRider]

Looking to change/fill the fluids on my 1990 Crown Supercoach and have the following questions.

1. Correct ATF for Allison MT647
2. Correct oil (straight 40?) for DD6-71TA
3. Coolant
4. Rear end gear oil
5. Any other fluids not mentioned.

[PNW_Steve]

Hey GW,

Your DD two stroke is very particular about the motor oil you feed it.

Low ash content straight 40 weight. The "standard" for years was Delo 100 - 40 weight. NOT Delo 400!!!!

Here is a site with some good info:Tejas Coach Works Factory DDC Oil Information Data Page

[Iceni John]

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!

[PNW_Steve]

Make sure and carry a few gallons with you.

There is a reason they call them "Green Leakers".

[GWRider]

Originally Posted by PNW_Steve

Hey GW,

Your DD two stroke is very particular about the motor oil you feed it.

Low ash content straight 40 weight. The "standard" for years was Delo 100 - 40 weight. NOT Delo 400!!!!

Here is a site with some good info:Tejas Coach Works Factory DDC Oil Information Data Page

I was not able to speak with the School District Mechanic to determine what they were using. This is very good information. Thanks!

[GWRider]

Originally Posted by Iceni John

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!

Also great information and much appreciated. Thanks!

[GWRider]

Originally Posted by PNW_Steve

Make sure and carry a few gallons with you.

There is a reason they call them "Green Leakers".

Something must be wrong with mine since it is not leaking (yet)…lol

[PNW_Steve]

Originally Posted by GWRider

Something must be wrong with mine since it is not leaking (yet)…lol

Have you started it yet?

[Booyah45828]

Originally Posted by GWRider

Something must be wrong with mine since it is not leaking (yet)…lol

It has to have oil in it to leak

No seriously, the joke was the only time a detroit doesn't leak is when it's out of oil.

[GWRider]

Originally Posted by PNW_Steve

Have you started it yet?

Actually, it has been started several times after we drove it back from CA. A trip to KHP for VIN inspection. A trip to have it washed etc. Oil shows full.

Also, looking at the Tejas link you provided, it states the following below. The way it is written makes it appear this happened prior to 1990 but not for 1990?

*** From Tejas Site ***
"There are more than one stories about bus engines and the fact that they leak. The biggest factor is the 2 cycle Detroit engine that powers the majority of all buses that were manufactured prior to 1990."

[GWRider]

Originally Posted by Booyah45828

It has to have oil in it to leak

No seriously, the joke was the only time a detroit doesn't leak is when it's out of oil.

Oil is full. It could be because the engine has approx. 66K on rebuild. Eventually, it will leak.