Should i Change it?
Thread Starter
Burning Brakes
Joined: Mar 2012
Posts: 1,200
Likes: 1
From: Belle River Ontario
2015 C3 of Year Finalist
Should i Change it?
Hey guys , quick question.
73 Vette , just bought it a few weeks ago , fantastic shape no noises no anything from the rear end but i have no idea when the differential fluid was changed.
I've read through all the posts here on changing the fluid and bought all the correct GM fluids and GM additive.
My question i guess would be , Should i change it if there's no problems?
I don't want to get myself into a mess here , my instinct is to change it as , like i said i have no idea when it was changed last and i want peace of mind knowing it's new.
Any thoughts?
Is there anything (can of worms ) i can be getting myself into?
Many thanks
By the way , the car has 53,000 original miles.
73 Vette , just bought it a few weeks ago , fantastic shape no noises no anything from the rear end but i have no idea when the differential fluid was changed.
I've read through all the posts here on changing the fluid and bought all the correct GM fluids and GM additive.
My question i guess would be , Should i change it if there's no problems?
I don't want to get myself into a mess here , my instinct is to change it as , like i said i have no idea when it was changed last and i want peace of mind knowing it's new.
Any thoughts?
Is there anything (can of worms ) i can be getting myself into?
Many thanks
By the way , the car has 53,000 original miles.
Burning Brakes
Joined: Oct 2011
Posts: 1,093
Likes: 2
From: long beach California
idk really but if your gonna change it are you gonna change the gasket? no way to do that with out pulling off the spring and taking the backing plate off. i would say pull the cap stick you finger as far in as you can. if the oil you pull out is clean you are in good shape for this season and add it to a list of things to do in the winter. if not or if you have too much metal in the oil change it. black doesn't always mean it is worn oil but it needs to be the right consistancy and free of large metal debris. 
congrats on the buy
congrats on the buy
Thread Starter
Burning Brakes
Joined: Mar 2012
Posts: 1,200
Likes: 1
From: Belle River Ontario
2015 C3 of Year Finalist
Thanks Jesse
I wasn't going to change the gasket at all , no leaks anywhere , i have a fluid transfer pump that should work pretty sweet.
Thanks again for the input
I wasn't going to change the gasket at all , no leaks anywhere , i have a fluid transfer pump that should work pretty sweet.
Thanks again for the input
CF Community Team
Joined: Oct 2004
Posts: 19,371
Likes: 5,250
From: Cape Cod, Mass.
2025 C6 of the Year Finalist - Unmodified
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
2021 C8 of the Year Finalist Unmodified
2020 Corvette of the Year Finalist (performance mods)
2019 C1 of Year Winner (performance mods)
2017 Corvette of the Year Finalist
2016 C2 of Year
2015 C3 of Year Finalist
I think it's a very good idea to change all the fluids on a car you just purchased. It is 39 years old. That way you have a baseline and you're starting with all new fluids. I use 80/90 gear oil and one bottle of GM posi lube. Do your figure eights to work it into the clutches.
Enjoy your new 73
Enjoy your new 73
Safety Car
Joined: Sep 2005
Posts: 4,063
Likes: 104
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
I think it's a very good idea to change all the fluids on a car you just purchased. It is 39 years old. That way you have a baseline and you're starting with all new fluids. I use 80/90 gear oil and one bottle of GM posi lube. Do your figure eights to work it into the clutches.
Enjoy your new 73
Enjoy your new 73
start "fresh" that way you know what was done and when it was done (baseline as described above).
Instructor
Joined: Sep 2008
Posts: 216
Likes: 0
From: Eugene OR
Here's what I did with my '72 before I finally got around to breaking open the diff:
1. Get a squeezy bottle, fluid pump or brake bleed pump and get the old stuff out as best you can.
2. Pour it through a white t-shirt to see if there's any nasties in it. If you find nasties take a picture and post it here before proceeding.
3. Snake a magnet down in there and pull out any metal that it finds. If you find any 'chunks' post a picture here before proceeding.
4. Put new fluid and the posi additive in.
5. Replace the fluid plug with a magnetic one.
Congrats and best of luck to you!
1. Get a squeezy bottle, fluid pump or brake bleed pump and get the old stuff out as best you can.
2. Pour it through a white t-shirt to see if there's any nasties in it. If you find nasties take a picture and post it here before proceeding.
3. Snake a magnet down in there and pull out any metal that it finds. If you find any 'chunks' post a picture here before proceeding.
4. Put new fluid and the posi additive in.
5. Replace the fluid plug with a magnetic one.
Congrats and best of luck to you!
