87 differential
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Get a cheap fluid pump from Harbor Freight. That is the easiest way to get the fluid out.
You can also install a drain plug. Some of the accessory catalogs have a drain plug that will self-thread after drilling a hole in the bottom of the diff case. You have to be careful as the location of the hole has to be fairly precise.
But for the most part, draining and refilling the diff gear oil is something that doesn't need to be done at regular intervals; maybe something like every 75-100K miles. Make sure to use a good GL-5 80W-90 gear oil and a bottle of GM positraction additive.
You can also install a drain plug. Some of the accessory catalogs have a drain plug that will self-thread after drilling a hole in the bottom of the diff case. You have to be careful as the location of the hole has to be fairly precise.
But for the most part, draining and refilling the diff gear oil is something that doesn't need to be done at regular intervals; maybe something like every 75-100K miles. Make sure to use a good GL-5 80W-90 gear oil and a bottle of GM positraction additive.
Moderator Emeritus
Joined: Jun 2002
Posts: 46,133
Likes: 111
From: Maryville Tn
CI 5 thru 12 Veteran
St. Jude Donor '09 thru '23
NCM Sinkhole Donor
Get a cheap fluid pump from Harbor Freight. That is the easiest way to get the fluid out.
You can also install a drain plug. Some of the accessory catalogs have a drain plug that will self-thread after drilling a hole in the bottom of the diff case. You have to be careful as the location of the hole has to be fairly precise.
But for the most part, draining and refilling the diff gear oil is something that doesn't need to be done at regular intervals; maybe something like every 75-100K miles. Make sure to use a good GL-5 80W-90 gear oil and a bottle of GM positraction additive.
You can also install a drain plug. Some of the accessory catalogs have a drain plug that will self-thread after drilling a hole in the bottom of the diff case. You have to be careful as the location of the hole has to be fairly precise.
But for the most part, draining and refilling the diff gear oil is something that doesn't need to be done at regular intervals; maybe something like every 75-100K miles. Make sure to use a good GL-5 80W-90 gear oil and a bottle of GM positraction additive.
Had my fluid changed in my '93 not too long after I bought the car, when it had 73,000 miles on it. That was almost seven years ago. I just went over 100,000 earlier this month. No problems. 
