Taken from 99 Pontiac Trans Am owners manual.

7,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer or has limited slip differential
Rotate Tires.

15,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Inspect air cleaner filter if you are driving in dusty conditions. Replace filter if necessary.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Change rear axle gear lube if it is used to pull a trailer.
Rotate tires.

22,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

30,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Change rear axle gear lube if it is used to pull a trailer.
Rotate tires.
Replace air cleaner filter.
Inspect fuel tank, cap and lines for damage or leaks. Inspect fuel cap gasket for any damage. Replace parts as needed.

37,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

45,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Inspect air cleaner filter if you are driving in dusty conditions. Replace filter if necessary.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Change rear axle gear lube if it is used to pull a trailer.
Rotate tires.

50,000 Miles
If you haven't used your vehicle under sever conditions listed previously and, therefore, haven't changed your automatic transmission fluid, change both the fluid and filter. Manual transmission fluid doesn't require change.

52,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

60,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Change rear axle gear lube if it is used to pull a trailer.
Rotate tires.
Inspect engine accessory drive belt.
Replace air cleaner filter.
Inspect fuel tank, cap and lines for damage or leaks. Inspect fuel cap gasket for any damage. Replace parts as needed.

67,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

75,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Inspect air cleaner filter if you are driving in dusty conditions. Replace filter if necessary.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Change rear axle gear lube if it is used to pull a trailer.
Rotate tires.

82,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

90,000 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change automatic transmission fluid if the vehicle is mainly driven under one or more of these conditions:
-In heavy city traffic where the outside temperature regularly reaches 90F (32C) or higher.
-In hilly or mountainous terrain.
-When doing frequent trailer towing.
-Uses such as a taxi, police or delivery service.
(If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83,000 km).)
Replace air cleaner filter.
Inspect fuel tank, cap and lines for damage or leaks. Inspect fuel cap gasket for any damage. Replace parts as needed.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

97,500 Miles
Check Oil Life Monitor. If engine oil and filter are changed, reset monitor.
Change the rear axle gear lubricant if the vehicle is used to pull a trailer.
Rotate tires.

100,000 Miles
Inspect spark plug wires.
Replace spark plugs
If you haven't used your vehicle under sever conditions listed previously and, therefore, haven't changed your automatic transmission fluid, change both the fluid and filter. Manual transmission fluid doesn't require change.

150,000 Miles
Drain, flush and refill cooling system (or every 60 months since last service, whichever occurs first). See "Engine Coolant" in the Index for what to use. Inspect hoses. Clean radiator, condenser, pressure cap and neck. Pressure test the cooling system and pressure cap.

The services show in this schedule up to 100,00 miles should be performed after 100,000 miles at the same intervals. The service shown at 150,000 miles should be performed at the same interval after 150,000 miles.

 

i just thought i'd throw .02 in...dexron III mercon will start to loose its lubricating effect around 30,000 so this should be done in both manual and automatic since both take the same fluid. also in my camaro's manual it never mentions rear end fluid change. and don't forget to inspect your bulbs and good stuf like that every once in awhile.

 

at my dealer this is our shedule:

oil change at 3,000 miles and again every 3,000 miles

rotate every 3,000 miles

start brake inspection at 9,000 miles then every 3,000 miles

at 15,000 air filter, fuel filter, battery service, oil additive, fuel additive, wiper blades, LOF, tire rotation, brake inspection, multi point inspection(belts, tires, leaks, bulbs etc..). Every 15,000 miles

at 25,000 automatic transmission flush, transmission additives, coolant system pressure test, LOF, tire rotation, brake inspection, Multi point inspection. Every 25,000 miles

at 30,000 coolant flush, coolant additives, fuel injector flush + 15k service. Every 30k miles.

at about 45k we recommend power steering flush, plus power steering additive.

at about 50k we recommend manual transmission service

at about 60k we recommend brake fluid flush, rear diff. service

at about 90k we recommend a spark plug change, automatic trans service including dropping pan and replacing transmission filter

 

My manual for 99 Firebird doesn't say anything about Rear Axle lube also. According Prince's scedule it doesn't need to be changed unless towing the trailer - yeah right!
Would you guys recommend changing at about 60k intervals?

Firebird!

 

I also have an 02 HD chevy truck w/6.0. At about 20,000 miles rthe LSD would no tunlock. I took it to 2 dealership for the complaint. They duplicated it and told me that I neede to change the fluid. I was furious that I had to change the fluid when the truck was still under warranty. Both dealers told me that GM does not have a time interval to change the diff fluid that it was lifetime unless you have a leak. I did change the fluid and it quit locking up. I now use only RP fluid and change it at about every 40,000 miles.

 

Besides oil changes when light comes on and air filters. Change everything at 60K and every 60k after. Exceipt hoses.....only if leaking.


Really; I would check fluids every oil change including diff., Main reason the yoke tend to leak on our cars and could burn up the diff. Sprayed all over the bottom of the car but not a drop on the ground. 60K on diff fluid sounds good if your doing it yourself ($) maybe a little longer if not. Check to see if burnt or the fluid is discolored.