Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
Thread Starter
Member
iTrader: (22)
Joined: Feb 2003
Posts: 371
Likes: 0
From: Claremont, North Carolina
Car: 1990 Formula Firebird
Engine: 305TBI w/ Functional Sport Hood CAI
Transmission: 700R4
Axle/Gears: SLP Posi and 3.23 Gears
Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
So I converted my 2.73 Open to a 3.23 w/ SLP Posi.
What I need to know is the capacity of the rear end of that year on a 1989 Formula Firebird (not sure how often this changed, if ever).
I also need to know what weight oil to use and if I should go complete synthetic or use a blended synthetic.
I'm sure this has been answered somewhere before, but I need to make sure this is correct
Posi Unit:
What I need to know is the capacity of the rear end of that year on a 1989 Formula Firebird (not sure how often this changed, if ever).
I also need to know what weight oil to use and if I should go complete synthetic or use a blended synthetic.
I'm sure this has been answered somewhere before, but I need to make sure this is correct

Posi Unit:
Joined: Sep 2005
Posts: 27,918
Likes: 2,448
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
Year doesn't matter.
Those are all about 2 qts; maybe just a scosche more. Varies a bit according to what gears & carrier are in them but not by much.
Yes pure synthetic is the better choice. Can't think of a good reason to dilute it with dinosaur juice.
Those are all about 2 qts; maybe just a scosche more. Varies a bit according to what gears & carrier are in them but not by much.
Yes pure synthetic is the better choice. Can't think of a good reason to dilute it with dinosaur juice.
Thread Starter
Member
iTrader: (22)
Joined: Feb 2003
Posts: 371
Likes: 0
From: Claremont, North Carolina
Car: 1990 Formula Firebird
Engine: 305TBI w/ Functional Sport Hood CAI
Transmission: 700R4
Axle/Gears: SLP Posi and 3.23 Gears
Re: Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
What weight of oil?
Joined: Sep 2005
Posts: 27,918
Likes: 2,448
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
75W-90; that being the stuff you can get the easiest.
Thread Starter
Member
iTrader: (22)
Joined: Feb 2003
Posts: 371
Likes: 0
From: Claremont, North Carolina
Car: 1990 Formula Firebird
Engine: 305TBI w/ Functional Sport Hood CAI
Transmission: 700R4
Axle/Gears: SLP Posi and 3.23 Gears
Re: Need Stock Specs Info on 1989 Rear End (Formula 2.73 Open)
Is there any reason to pay more for stuff like Royal Purple or Lucas vs. something like Mobile 1 (all same weights and synthetics)
Thread
Thread Starter
Forum
Replies
Last Post
hectre13
Engine/Drivetrain/Suspension Parts for Sale
2
Dec 11, 2023 08:14 AM
AkDrifted
Engine/Drivetrain/Suspension Parts for Sale
6
Aug 17, 2015 07:45 PM
novaderrik
Transmissions and Drivetrain
3
Aug 10, 2015 12:44 PM







