Need additive if you have limited slip differential. Keeps clutches from sticking and banging. My 68's sounded like it needed a rebuild. One bottle of additive drive it and it works its magic.
@@mariano4003 Go to your local Chevy dealer, they might have someone still knows how to work on C3 Vettes Used it more than 20 years ago, sure don't remember may have something better now
I like to use one of those cheap fluid transfer pumps from Harbor Freight. less messy than using the suction pump over and over again, just pump the used into an empty gallon oil container.
Amsoil has gear oil in a bag now. You can roll it up like a tooth paste tube to empty it. If you go to my page you can see me fill the diff on my 74 Lemans with it. Very handy. I imagine it won’t be long before other do the same.
You better watch for fakes on Amazon. They already sell fake Motorcraft ignition coils that China makes and other people sell. I wonder why the price is cheaper. Hmm. I still get my 80w90 gear oil from GM Parts and still have some posi additive from the 60’s or 70’s for my 70 Z28. I also use the same suction unit to FILL my axle and transmission case. You’ll also never get all the old oil out without removing the cover. But I see a Vette would be a beeatch to remove. With a posi unit, once the fluid is changed, go find an empty parking lot and do 5 figure 8’s one way then 5 the other way for a total of 10 to mix up the gear oil into the posi clutch packs.
Watching the video and I can smell the nasty gear oil. Can the plug be changed to one where an extension or breaker can be used to speed up the process?
If you have posi-traction this advice is spot on. It matters what you put in that differential. Its still critical on non locking rear difs, but not as much as a Posi.
Starting with the 70 models, Positraction became standard but for 68 and 69 it remained optional but was a required option on all big blocks. So your 68 and 69 327/300, 327/350, 350/300 and 350/350 could have an open rear diff but not many did, less than 3,400 cars total for both years combined. 😀
Fantastic video!! i have subscribed!!! , excellent info... I do deviate from the GM gospel on gear lube though Ben, I have had 3 c3 corvettes 1972, 1980, 1981 which is my present C3. I know it's always good to be a purest and go acdelco /gm whenever possible, but i have always used AMSOIL 75W 110W SEVERE DUTY GEAR LUBE AND 4 0Z. GM POSI, and I have over a total 0f 300,000 c3 miles on this stuff and I cannot tell you how clean my rear pumpkin is when I drain and fill it.
One note..if you never worked with 80-90W oil it smells like burnt oil even though it is new...engine oil has a slight smell but gear oil has a distinct smell almost like something is burning ....Just a note I wanted to mention. Ben Corvette is the MAN!! 4 real.
When I first got my C3 back in 87, ya im dating myself haha, I didn't put any additive. I always wondered why my rear end chattered when I turned. There was no internet back then :)
The easy way drill a 3/8 hole in that low spot on the diff drain it tap it 1/8 npt from there on out it's very easy because you have a drain plug! At least that's the way I did mine
I always tell people that my main qualification for working on cars is that I am not afraid to get greasy...with the exception of old gear oil...that stuff is nasty!! But Ben you're shaming me into getting out there and doing to my C3...ugh.
And when you do it my way you get it all including any metal shavingswhat you're after a new gear installation is normal and to be expected in small amounts! Just another way to do it Ben you're doing a fine job
What type of fluid should I use? A 74 Corvette Stingray. I read somewhere that temp can affect it and I don’t wanna fuck up my “new” car. I’m in NC.. It doesn’t need it done, it only had 16K miles. But I want to know the fluids are correct and new. Please help.
Part number for the gear oil is nearly impossible to find now for less than $32 a quart. Can you recommend a replacement part number or a different brand or something, Ben?
I have a 78 C3 and your videos and advice are helping me a ton. I ordered The AC DELCO gear oil and additive Ben recommends for C3 diffs. Ordered and received it from Amazon. But they sent me 10-4108 synthetic gear oil instead of the 10-4061 Ben recommends. Anyone know if the 10-4108 is possibly an even better option?
Does anybody have a reliable source for the correct part number of Delco gear lube for C-3's (with positraction)? My original 72 owners manual specifies all sorts of things for the car but for the differential fluid it just says "see the dealer". There are too many similar AC Delco gear oil part numbers. 10-40xx.
Hi Ben love the channel I have a question had it to 2 different garages and they seen nothing hopefully you can tell me what might be wrong pulled my 1992 c4 out of the garage when got it out went back to close the garage door an noticed a red puddle on the floor this puddle was right beside the driver. Side rear wheel on the in side of the wheel hopefully you can help thanks Jeff sorry forgot to tell you later I when back to clean it up it started to harden like wax and it started to break and was white in side
Sorry forgot to tell you that the puddle was a bright red after a little while I went to clean it and it started to dry like wax when a piece of it started to break off it was white inside 😅
From the Thumbnail, I thought you were going to say the best way to change your differential fluid is to put in a new differential that has been pre-filled with fluid.
First thing, I just want to say your vids are extremely helpful and I’m always looking out for the next one to come out. I’m getting ready to change mine out and was wondering if there’s supposed to be a gasket for the filler plug?
I was just going to do this in my '74. Thanks! I've heard you should do figure eights in a parking lot after to get it distributed evenly. Is that true?