Differential fluid change - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DoobieBrother · 08-08-2007, 06:37 PM

Ok, I know these trucks (`68) generally use 90 weight gear lube. Couple of questions, though.

How many of you guys are running synthetic.
If I did go synthetic, could there be any issues given that I have a hunch that if the fluid has ever been changed, it was LONG ago?
Are you guys replacing with a gasket on the cover, or are you just using some sealer?
Favorite sealer?

Longhorn Man · 08-08-2007, 07:24 PM

You'll have no issues at all going to synthetic other than the cost. That oil will be good dang near forever as long as it does not get contaminated.
I use sealer, the Right Stuff is awsome, but expensive. I get it for free, same with the oils, so I use them.

cdowns · 08-08-2007, 07:24 PM

i always like to wash out the insides with kerosene (windex spray bottle) when changing out really old fluid in the rear. i always change to synthetic(mostly royal purple) i just go with the original type gasket held in place with permatex aviation form a gasket// the good thing with royal purple if your running posi is you dont need the posi additive// i run royal purple in my trannies also

Longhorn Man · 08-08-2007, 08:22 PM

brake clean is another goos solvent to clean the rear end out with, it evaporates, leaves no film, and comes in arasol cans.

BCOWANWHEELS · 08-08-2007, 09:55 PM

wash out diff with starting fluid, it cuts the old oil great, has pressure behind it, i use castrol senthetic 85w140 and seal it up with permatex ultra black silicone. jmo
bob

Texasdeere · 08-08-2007, 10:39 PM

I like to run synthetic in the drivetrain, especially the rear end. Synthetic is good stuff but cost too much to use in the engine for me.

DoobieBrother · 08-08-2007, 10:44 PM

Ok. Thanks for the info guys. Should be gett'n after it this weekend.

08-08-2007, 06:37 PM	#1
DoobieBrother Registered User Join Date: Aug 2006 Location: US Posts: 184	Differential fluid change Ok, I know these trucks (`68) generally use 90 weight gear lube. Couple of questions, though. How many of you guys are running synthetic. If I did go synthetic, could there be any issues given that I have a hunch that if the fluid has ever been changed, it was LONG ago? Are you guys replacing with a gasket on the cover, or are you just using some sealer? Favorite sealer?

08-08-2007, 07:24 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Differential fluid change You'll have no issues at all going to synthetic other than the cost. That oil will be good dang near forever as long as it does not get contaminated. I use sealer, the Right Stuff is awsome, but expensive. I get it for free, same with the oils, so I use them.

08-08-2007, 07:24 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Differential fluid change i always like to wash out the insides with kerosene (windex spray bottle) when changing out really old fluid in the rear. i always change to synthetic(mostly royal purple) i just go with the original type gasket held in place with permatex aviation form a gasket// the good thing with royal purple if your running posi is you dont need the posi additive// i run royal purple in my trannies also __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-08-2007, 08:22 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Differential fluid change brake clean is another goos solvent to clean the rear end out with, it evaporates, leaves no film, and comes in arasol cans.

08-08-2007, 09:55 PM	#5
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: Differential fluid change wash out diff with starting fluid, it cuts the old oil great, has pressure behind it, i use castrol senthetic 85w140 and seal it up with permatex ultra black silicone. jmo bob __________________ I BELIEVE IN JOHN 3:16

08-08-2007, 10:39 PM	#6
Texasdeere Registered User Join Date: Sep 2006 Location: League City, Texas Posts: 732	Re: Differential fluid change I like to run synthetic in the drivetrain, especially the rear end. Synthetic is good stuff but cost too much to use in the engine for me.

08-08-2007, 10:44 PM	#7
DoobieBrother Registered User Join Date: Aug 2006 Location: US Posts: 184	Re: Differential fluid change Ok. Thanks for the info guys. Should be gett'n after it this weekend.



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