Dana 20 Gear Oil

[c2computer]

What do you guys use for the Dana 20 Gear oil? I have two manuals that have conflicting answers (80w/90 and 140w) and have never changed it yet. Thanks.

 

[Josh]

i have been using 50w motor oil

 

[c2computer]

Thanks, I think that is what I have in there now.

 

[74bronc]

50W motor oil and 90w are about the same viscosity. They have different viscosity #'s because they are tested at different temperatures to find the viscosity points. I just got Amsoil 75w-90 Synthetic for my transfer.

 

[c2computer]

So SAE 50 is ok to put in or is there something better?

 

[Broncobowsher]

This may take a little to explaine everything, so here we go....<br><br>50 weight engine oil and 90 weight gear oil are about the same viscosity. I was just looking it up in my Phillips 66 petroulium handbook the other night. I think the 50 weight has a tighter window to fall into the 50 weight grade. So wiht both oils being the same weight what are the differences...<br><br>50 weight engine oil was designed to be run in engines. Mainly it is a detergant oil. Before you go off thinking detergent is good, there is a little more to it. What detergant does is keep the dirt in suspension in the oil. Why it does this is so the oil filter can capture it. Old engines running non-detergant oil would build up sludge and require the pan to be pulled off and the gunk scraped out every once in a while. <br><br>90 weight gear oil is designed for gears and bearings. it has high pressure additives and is ment for gearboxes. It is a non detergant oil so the dirt that gets in the box just settles to the bottom where it sits. <br><br>Basicly engine oil in a gear box will keep the dirt in suspension and circulate it around. Why would you want to do that?<br><br>As for the factory fill of 50 weight, it was probably a non detergant blend made just for ford (the factorys can get just about anything made for them).<br><br>I have never seen a straight 50 weight nondetergant oil. But, you can find a 90 weight synthetic.<br><br>Did I ramble on enough? I have a few more posts to read during lunch....

 

[c2computer]

So stick with the 85/90 gear oil? I appreicate the help.

 

[74bronc]

[quote author=Broncobowsher link=board=5;threadid=10146;start=0#73522 date=1034623467]<br>This may take a little to explaine everything, so here we go....<br><br>50 weight engine oil and 90 weight gear oil are about the same viscosity. I was just looking it up in my Phillips 66 petroulium handbook the other night. I think the 50 weight has a tighter window to fall into the 50 weight grade. So wiht both oils being the same weight what are the differences...<br><br>50 weight engine oil was designed to be run in engines. Mainly it is a detergant oil. Before you go off thinking detergent is good, there is a little more to it. What detergant does is keep the dirt in suspension in the oil. Why it does this is so the oil filter can capture it. Old engines running non-detergant oil would build up sludge and require the pan to be pulled off and the gunk scraped out every once in a while. <br><br>90 weight gear oil is designed for gears and bearings. it has high pressure additives and is ment for gearboxes. It is a non detergant oil so the dirt that gets in the box just settles to the bottom where it sits. <br><br>Basicly engine oil in a gear box will keep the dirt in suspension and circulate it around. Why would you want to do that?<br><br>As for the factory fill of 50 weight, it was probably a non detergant blend made just for ford (the factorys can get just about anything made for them).<br><br>I have never seen a straight 50 weight nondetergant oil. But, you can find a 90 weight synthetic.<br><br>Did I ramble on enough? I have a few more posts to read during lunch....<br>[/quote]<br><br>Exactly right. This is exactly what my research indicated when I checked it out. I am running straight 50w in it right now and it works good, easier to shift the case than with 90w (non-synthetic) but it does leak more with this oil in it. I am going with the 90w synthetic because of its stability at all temps, lubricates better (should make it easy to shift the case like the 50w) and it has been proven to be a better all around gear oil. I ran petroleum based 90w for about 4 years before I knew the book called for 50w, so I wanted to try it.

 

[c2computer]

I think I'll put the 50w in it now, see how it works. I just want to get some new oil in there since I don't know when/if it was changed from the previous owner. Thanks.