The Amsoil corporate website indicates the Severe Gear 75w-90 lube oil is compatible with most LSD's. Does anyone know what the percentage of friction modifer is in a quart of the lube? I'm guessing that it would be 4% to 6%.
Amsoil Severe Gear - Friction Modifier?
- Thread starter billmac
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I doubt if the FM % is that high. However, no one posting to this site has access to the actual formulation. I would say it's under 4%.
Molakule may want chime in.
Molakule may want chime in.
After the Series 2000 gear lube came out, I called Amsoil technical support regarding the % of FM and I believe they told me it was 5%. Of course that's been awhile back and this is a different product but that's what I based my estimate on.
We worry about everything!
Well the actually carrier oil and FM might be 5%, but it seems unlikely the actual chemical doing the FM'ing is a total of 5% of the formulation.
Well the actually carrier oil and FM might be 5%, but it seems unlikely the actual chemical doing the FM'ing is a total of 5% of the formulation.
MolaKule, are you saying that the 4 oz bottle of FM that I buy at the Dodge parts place has very little FM and that it's mostly carrier? It sure looks like FM to me when I pour it.
My Dodge 2500 CTD pickup has a Dana Model 70 LSD and according to Dana Corp. this setup requires 6% to 8% FM to function properly. The capacity of the diff is 7 pints (2WD). If the Amsoil Severe Gear lube only has 0.8% to 1.5% FM per quart then that means 7 pints will have slightly over 2ozs of FM (using 1.5%). To get to the Dana spec of 6%-8%, I will need to add 6 to 7 ozs. of FM. That doesn't sound right to me. In the past, I've only had to add 2 to 3 ozs of FM to make the diff work properly with Amsoil Series 2000 gear lube.
Believe me the manufacturer's "FM" additive is not 100% FM. So the DANA recommendation follows the same lines. I therefore think your calcs are not exactly correct.
Go with SGR straight. Unlikely you'll need the additive, but if you do use Dodge or Amsoil additive at 1/2 the amount recommended.
Go with SGR straight. Unlikely you'll need the additive, but if you do use Dodge or Amsoil additive at 1/2 the amount recommended.
MolaKule
Staff member
The actual percentage of LS friction modifier in diffy lubes from the lube manf. is on the order of 0.8% to 1.5%, since it is a specially compounded and concentrated phosphorus-based product (a thick phoshorus ester).
The 4 or 7 oz. stuff you get in a tube from say Autozone or wherever has been diluted so it can be poured easily.
Now the friction modifier to reduce bulk friction and viscous drag is usually provided by one of the base oil components and is generally a POE ester.
BTW, anytime you handle this stuff, please glove since phosphorus esters have a propensity for damaging the liver.
I'm using SVG(75W-90) in my front and rear diffs with E-lockers and I have had absolutely no issues with the lubricant.I called Eaton before I used the SVG and they told me there was no problem using this stuff with their traction control devices(LSD,Posi,Lockers).But like Pablo said, Amsoil makes a Friction Modifier called Slip Lock just in case you get chatter.
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