help me understand 80w90 vs 75w90

[thatguy]

The manual for my JD 2320 calls for 80w90 in the front axle. It lists no other recommended weights.

The rotary cutter manual gives you a chart showing the temperature range of a whole bunch of different weight gear oils. Obviously the a 75w90 gives you a greater range than the 80w90.

I was going to buy some amsoil 75w90 for my pick up differentials - Is there any reason I cant use the 75w90 instead of the 80w90 in the tractor to keep it simpler?

thanks

Brian

 

[frank_miller]

The manual for my JD 2320 calls for 80w90 in the front axle. It lists no other recommended weights.

The rotary cutter manual gives you a chart showing the temperature range of a whole bunch of different weight gear oils. Obviously the a 75w90 gives you a greater range than the 80w90.

I was going to buy some amsoil 75w90 for my pick up differentials - Is there any reason I cant use the 75w90 instead of the 80w90 in the tractor to keep it simpler?

thanks

Brian

use 75w-90 and be very happy. I have used their series 2000 stuff in my bx22 and performed great. It is really fill and forget!

 

[RalphVa]

Use the 75w-90.

It's like using 0w30 engine oil instead of 5w-30. The 0w-30 is better.

Ralph

 

[Matt_Jr]

The first number(75) represents the viscosity of the oil at cold temperatures and the second(90) represents the viscosity at warm temeperatures. The first number is calculated differently than the second number and that's why the first number isn't higher. The second number is what the viscosity will be when the tractor is warmed up(most of the time it's being used), therefore it's crucial that the last number is 90. The first number being lower(75) rather than 80 is better yet because it will flow and lubricate before the tractor is warmed up. It can be confusing and even sounds backwards but that's the way it is. The chemists that decided on these measuring systems just thaught it would be funny to confuse the rest of us.

 

[RWEST]

The chemists that decided on these measuring systems just thaught it would be funny to confuse the rest of us

And, to give us a reason to have forums like this and BITOG!!

 

[Z71]

fyi

snippet from a GM Technical Bulletins

This bulletin is being issued to inform dealers about the compatibility and usage of the new Fuel Efficient SAE 75W-90 Synthetic Axle Lubricant,.....................


.................
It is recommended that synthetic lubricant be used when changing rear axle lubricant for the following reasons:

Potential fuel economy
Lower operating temperature under severe usage conditions ........


As a product improvement, this new lubricant has been released into 1999 current production C/K vehicles built after the above VIN breakpoints

 

[DieselPower]

Most all 80W/90 gear oils are conventional, 75W/90 is usually synthetic. That's the main difference and as far as using one in place of the other it's not a problem as long as it's the correct spec.