Is anyone with a Dana 70 open diff in a Class C motorhome running synthetic 75w90 oil?
Based on the official Spicer manual, it calls for 80w90 except in steering situations (dually steering??) when it calls for 85w140.
Quote
DIFFERENTIAL LUBRICATION
It is not our intent to recommend any particular brand or make of lubricant for the Spicer hypoid axle.
However, an S.A.E. SOW-90 multi-purpose gear lubricant meeting Mil. Spec. L-2105-D, and suitable for 1A.P.I.,
Service Classification GL-5, is suggested as a minimum requirement
Source; page 5-1: https://media.spicerparts.com/cfs/files/media/Nwh6LfbHWPgh9aKS3/5312-9.pdf?store=original
It does go on to say you should use whatever vehicle manufacturer it got put on says to use, but needless to say, I don't have the 1985 owner's manual since I'm not the original owner.
The gear oil was probably the original from 1985 based on how bad it looked when I drained it back around August. I put in cheap SuperTech conventional 80w90 ($15/gal) as a means of cleaning it up before I put in more expensive synthetic. It's been roughly 1400 miles so far. In about another 800mi/1 month, I will dump it and put in synthetic, when I get to a place I can work on it without hassle. There has been no noise from the diff so it seems to be playing okay in there.
For some odd reason, Super Tech Full Synthetic Gear Lubricant 75W-90 is dirt cheap vs 75w140. Since the tech spec (roughly) matches the Spicer manual, I would think it should be fine.
I never tow, so that's not a factor. I stay at 55-60mph most of the time for better fuel economy so it's not being run as hard as it could be. In addition, I am full time RVer, and I typically stay out of very hot places. 85-90 is usually the highest I ever see and if it's that warm, you can bet I'm already heading north.
It's got a 6.9L IDI (with ATS 085 turbo) and a C6 (3sp A/T) up front, with 4.10 gears in the D70, for those wondering.
I reckon that the ST full synthetic 75w90 will be fine for my application given those operating conditions, but I'd like to hear other's input. Being full synth, it should hold up better than conventional, even if it gets hotter now and then, a few times a year.
Below are the pics I took when I drained it. Due to the rotation of the carrier, it was hard to see inside. I got my camera positioned just well to take a shot and it's definitely open, not LS.
The RV itself:
Based on the official Spicer manual, it calls for 80w90 except in steering situations (dually steering??) when it calls for 85w140.
Quote
DIFFERENTIAL LUBRICATION
It is not our intent to recommend any particular brand or make of lubricant for the Spicer hypoid axle.
However, an S.A.E. SOW-90 multi-purpose gear lubricant meeting Mil. Spec. L-2105-D, and suitable for 1A.P.I.,
Service Classification GL-5, is suggested as a minimum requirement
Source; page 5-1: https://media.spicerparts.com/cfs/files/media/Nwh6LfbHWPgh9aKS3/5312-9.pdf?store=original
It does go on to say you should use whatever vehicle manufacturer it got put on says to use, but needless to say, I don't have the 1985 owner's manual since I'm not the original owner.
The gear oil was probably the original from 1985 based on how bad it looked when I drained it back around August. I put in cheap SuperTech conventional 80w90 ($15/gal) as a means of cleaning it up before I put in more expensive synthetic. It's been roughly 1400 miles so far. In about another 800mi/1 month, I will dump it and put in synthetic, when I get to a place I can work on it without hassle. There has been no noise from the diff so it seems to be playing okay in there.
For some odd reason, Super Tech Full Synthetic Gear Lubricant 75W-90 is dirt cheap vs 75w140. Since the tech spec (roughly) matches the Spicer manual, I would think it should be fine.
I never tow, so that's not a factor. I stay at 55-60mph most of the time for better fuel economy so it's not being run as hard as it could be. In addition, I am full time RVer, and I typically stay out of very hot places. 85-90 is usually the highest I ever see and if it's that warm, you can bet I'm already heading north.
It's got a 6.9L IDI (with ATS 085 turbo) and a C6 (3sp A/T) up front, with 4.10 gears in the D70, for those wondering.
I reckon that the ST full synthetic 75w90 will be fine for my application given those operating conditions, but I'd like to hear other's input. Being full synth, it should hold up better than conventional, even if it gets hotter now and then, a few times a year.
Below are the pics I took when I drained it. Due to the rotation of the carrier, it was hard to see inside. I got my camera positioned just well to take a shot and it's definitely open, not LS.
The RV itself: