75W-90 or 75W-140 for rear diff ?

[ANGST]

75W-90 or 75W-140 for rear diff ?

99% DD , 2 track days a year. A couple Autocross .

Novice level on track pushing 7/10th


What do you suggest ?

Sponsored

 

[ddozier]

75W-90 or 75W-140 for rear diff ?

99% DD , 2 track days a year. A couple Autocross .

Novice level on track pushing 7/10th


What do you suggest ?

Here is how I see it, the track matters a lot in this decision. If you are tracking at a small low speed track twice a year I would run the 75W-90 and change it after each event. Changing the fluid is easy and can be done by saving an old antifreeze jug and buying one of these hand pumps to pump the diff fluid of choice back into the diff.
https://www.harborfreight.com/gear-oil-and-fluid-pump-61746.html

If your home track is something like Road America or Road Atlanta were even novice drivers will see sustained high speeds then I would run the heavier weight oil and change it at the end of your track season back to the lighter weight 75W-90. This way in the colder months you will have a lighter weight gear oil and the summer (track) months you will have a little more protection for track use.

All this is assuming you are tracking a single session and not double stinting or sharing the car with another driver running in another run group at the event. The gear oil will hold up fine as long as it has time to cool between sessions and you are running 25min sessions or less. If you end up sharing the car or running longer than 25min you will want to add a cooler to the diff to keep temps in check.

Dave

 

[Competition Orange]

I've been running 75w110. Last year did 6 track days, lots of autocross and 12k miles. It came out looking like poo. Should have changed it mid season.

So, that's what I'm doing this year, 2 changes per year, I'll add a cooler once the car is more dedicated to track work.

 

[dgc333]

There is a TSB that came out in the mid 2000s directing dealerships to service all vehicles with an 8.8 to use 75w-140. Also, if you buy gears from Ford Performance the installation instructions state to use 75w-140.

 

[JohnD]

I have BG 75W-140. It for sure helps my car on track to keep diff temps lower. If you're a fuel economy watcher you might not want to do it, the heavier oil does cost some fuel economy, not much but it seems about 1 to 2 mpg worse.

 

[Austinj427]

I just swapped mine to Gibbs 75 90 because I was concerned about warranty with 75 140.

The more I think about it, the more I realize I should have just gone 75 140. My buddy went to 75 140 and it cured every problem he was having with his factory diff in his Camaro.

 

[ANGST]

I just swapped mine to Gibbs 75 90 because I was concerned about warranty with 75 140.

The more I think about it, the more I realize I should have just gone 75 140. My buddy went to 75 140 and it cured every problem he was having with his factory diff in his Camaro.

S197's with the torsen called for 75-140 . I am not sure how different they are compared to the s550

good info here :


https://bit.ly/2uYzsrH

Sponsored