I'm starting out with 2 new gear this year.

Both are race only.

8 3/4 4.30 US Gear with spool in 742 case

Dana 60 4.56 Richmond Pro gears

I've never replaced the lube in the past but I've seen some posts that suggest that I should.

Do you think it's necessary?

If so, could I just suck out some out of the bottom and just replace it.

Or is it a waste of time and money?

I hope not. I never did on mine.

only if you see metal shavings when draining it out.

Run it!! waste your time,Save your money, Put that time some where else

My new Strange says change it after 50 miles but that is with street gears. FWIW

what lube are you guys running in the rear track car

I have been running mobile 1 syn 75-90 for 7 years and way over a 1000 passes and hundreds of street miles in mine.

My differential guy said that the coating on the gears is actually abrasive and not good for the bearings. But the amount of it worn off during break-in doesn't necessarily require a lube change. But it doesn't hurt.

I would think that the ideal proceedure would be like for an engine break-in. Break it in with conventional lube then change to synthetic. It's a pain to change just for the sake of changing the fluid, but my next housing will have a drain plug with a magnet.

I use Amsoil Severe Gear 75W-90.

i change it after breakin, and annually thereafter. maybe that's why my 8.75 lasted so long before disintegrating?