leaky 4104 (oil); how high viscocity can I run?

[JT4104]

Hi All:

I know we are supposed to run 40 wt straight oil in the summer in our 671s, but can I run 50 weight in the hot summer to keep the engine from weeping oil?  I loose about 1/2 gallon every 700 miles, coming out mostly on the engine, not the airbox drains.  I don't even know if 50 wt oil is available, just asking. 

Thx,

JT4104

[Dallas]

Sure you can use 50Wt, just make sure that it's API Cf-2.

Detroit diesel TSB is 7SE270 and is found at:

http://www.detroitdiesel.com/support/on-highway/manuals/Lubricants_Fuels_Coolants/index.asp

But wouldn't it be cheaper and easier to fix the xisting leaks?

Where are you leaking oil from exactly?

Good Luck,

Dallas

[gus]

JT,

My 4104 does the same thing. I've decided that most of it is coming out of the rear main seal but don't really know for sure. It is a very hard job pinning down those leaks. I've managed to stop a few but it is still bad. One other place I suspect is the air box cover plates on the back side of the engine under the exh manifolds.

The worst leak I had was the connector fitting loose at the governor. It carries oil mist from the crankcase to lube the governor. It was only oil mist but the mess it caused was unbelievable.

I decided to keep looking as I drive it because the power is good and the engine runs very well. I am going to take it to a good local DD guy eventually but I'm not prepared to spend thousands of $$ just to stop the leaks.

I prefer to call the stuff covering the rear of the bus, "Corrosion Prevention Fluid" and keep wiping it off!!

[JT4104]

Yes most of it on mine comes from the rear main seal and some from the governer area as well, but it seems to seep from many other gaskets, as well as air box cover plates.  But the power is good and I'm not ready for an out of frame overhaul yet, so I thought that 50 weight in our hot climate could help the situation a little.

[gus]

JT,

50W might help, it can't hurt in this weather.

When I changed from 30W to 40W I couldn't tell any difference. I ran it almost a year on 30W because I couldn't find any 40W. I live in a very small town.

[Hartley]

Get some LUCAS oil additive ( gallon jugs ) It will help slow things down a little...

Works for me....

[gus]

Does Lucas thicken the oil or swell the seal??