i need to go get the oil i want sinthetic but im not finding what weight to get and the parts place cant look it up. anyone know off hand real quick i need to get there before they close

 

o come on guys, i need to get this done, someone has to know this

 

75/140 is the proper rear end weight, gear oil

 

so y does no one seem to carty that weight?

 

amsoil carrys that weight and is synthetic

 

problem is finding someone in bakersfield that carrys amsoil thats open before 8 or after 6....

 

75w140 is great if you are in a really hot climate or towing heavy loads a lot. If you are in a colder climate and not towing a lot, I would recommend 75w90. This is what I run and even with towing, the rear end never gets too hot.

You don't have to get exactly the weight oil that we are recommending, you want something close to it. For example substituting 80w90 for 75w90 would be fine. Thicker weights are better for heavier loads where more heat is built up. I have also seen 75w110 which would be a good compromise for some people. You want to get an oil that is somewhere around 75w90/140 and that is differential fluid.

If you have an lsd, you might need some form of a friction modifier.

 

ya i want to get a synthetic with the additive in it. it gets HOT here and i tow some pritty hefty loads over some big hills. so 75w140 is probibly what i need but can only find the 85w140 or 80w140s and those arnt in synthitic

 

The inportant # is the 140! 80w-140 is just as usable! They are all 140 viscosity after reaching about 160*.

Your CTD probably calls for 75w-90 or 80w-90... like mine, but in your warmer climate I would (and do) use an XXw-140 wt Gear Lube.

If towing at all, the 140 is important.

RJ

 

ok well when i get off ill start looking for a 140 in eather amsoil or royal purple they seem to be the heavy favs around here

 

i have been woundering the same thing...about the weights. but will it hurt my the diff. if i am runing 75W90. it usually stays around 90-95* around here in texas and i do tow often.

 

psd tuner,

There are too many variables to tell whether you are hurting your diff with too lightweight of an oil. The diff temp depends on the tolerances of the components in it, whether it is a LSD, the oil in it, and your driving style. Given your situation, next time you change the oil, I would go to something like 75w140 to be safe.

RowJ made a good point about what part of the number for split weight oil is important. Oversimplifying a little, the first number is important when the oil is cold so when you are just starting to drive the truck. If this number is too high, the oil will be really viscous until the diff warms up some. The second number is important once the oil gets warm. The higher the number, the better the protection against high heat.

 

right i remember what the numbers in the weights of oil mean. i think next time i change the oil i will go with a 75W140.

 

finaly found some royal purple 75w140, gona do it tonight, hope its not to low

 

Bingo! RowJ hits the homer again..

IMO, the use of a syn alleviates the need for a thinner lube in wintertime, and rear axle failures are far more likely from 1) viscosity failure and 2) low fluid level than from running a lube that's slightly thicker and takes a few seconds longer to get up to temp.

The gear oil I use is the Redline Shockproof. This is some serious gear lube. It doesn't have as much fm in it as other lubes, so if you have a
limited slip, you may need to add more friction mod.

http://redlineoil.com/products_gearl...bCategoryID=16


Now, if only we could get Redline to put the stuff in a remotely useable bottle. The current package is clumsy and doesn't flex-- useless for dumping it in tight quarters.