ziller

Ziller pumped out all the differential fluid from the 1979 and replaced it with Royal Purple - Max Gear High - Performance Gear Oil (75w-90). The bottle sez that it is limited slip.

Question: Is this good enough? Or is the GM special formula and additive required?

Thanks in advance.

ziller

0Willcox Corvette

Ziller..

I'm not a huge fan of Royal Purple.. but yes.. you'll need the additive. 1052358 is the old GM number...

I'm not sure of why you drained the rear but if the clutches were sticking and you have what we call "waddle" when turning corners then I would put two bottles in.. drive it in a parking lot doing figure 8's.. then drive it some more on straights... Drain and refill with standard old gear lube and 1 bottle of additive. If the clutches were sticking this should clear it up.. if not.. then you might consider pulling the rear and replacing the clutches.

IMHO,


Willcox

BTGRN75

IYO -how often would you recommend rear end (with posi) fluid changes?

papafrancisco

help please

427Hotrod

I've run Royal Purple with no additives for years and it works great in posi's. Never seen anything but good stuff out of them so far.

JIM

jimo

[QUOTE=Willcox Corvette;1579022998]Ziller..

I'm not a huge fan of Royal Purple.. but yes.. you'll need the additive. 1052358 is the old GM number...

I'm not sure of why you drained the rear but if the clutches were sticking and you have what we call "waddle" when turning corners then I would put two bottles in.. drive it in a parking lot doing figure 8's.. then drive it some more on straights... Drain and refill with standard old gear lube and 1 bottle of additive. If the clutches were sticking this should clear it up.. if not.. then you might consider pulling the rear and replacing the clutches.

IMHO,

I added 2 bottles of additive when I had the same problem and it did the trick!!

hunt4cleanair

Is there two questions there?

You ask about the differential drain plug but refer to a 79 automatic...no difference between auto and manual transmission regarding changing the differential fluid on a 79. I see the C5 logo so you may be assuming the transmission/differential is one unit as with C5 but this is not the case for C3.

So having said all that, the differential plug is on the passenger side above rear leaf spring. Should be a GM red tag that says "USE LIMITED SLIP DIFF. LUBRICANT ONLY" To drain the fluid you have to use a fluid pump or pull the cover which you do not want to do unless absolutely necessary...like you have a differential leak and need to replace the gasket

mds3013

Drian plug here. mike...

Paul L

Just a tip. Use an 8-point (not 6- or 12-) 5/8" socket to get that plug out.