detjoe Posted May 6, 2007 Report Share Posted May 6, 2007 I am going to change my diff fluids but last time I was at autozone they only hade 75w-90 and no 80w-90. What is the deal?? can I use the same synthtic fluid front and rear??? I know to use syn and no additive but dont know about using a different weight oil, this is where someone can teach me about the oil numbers cause I dont know what is what...but I need to change them asap. thanks Quote Link to comment Share on other sites More sharing options...
Rausche Posted May 6, 2007 Report Share Posted May 6, 2007 Look in your owners manual. It should have all the weights and capacities in there. Also, if you can't find what you're looking for locally and decide to order it, I personally recommend Royal Purple. It's expensive, but it's great stuff imo. Quote Link to comment Share on other sites More sharing options...
detjoe Posted May 6, 2007 Author Report Share Posted May 6, 2007 I checked with Mr P's how to for what type and just get confused when they done have two different viscosities at the store. I am going to just to the front then, untill I find out if it is ok for the back?? Quote Link to comment Share on other sites More sharing options...
misterp Posted May 6, 2007 Report Share Posted May 6, 2007 The book says to use 80W-90, but the only thing I can find in the stores is synthetic 75W-90 and it works well if not better. Don't add any other additives. Mr. P. Quote Link to comment Share on other sites More sharing options...
Holty Posted May 7, 2007 Report Share Posted May 7, 2007 why no additives? Quote Link to comment Share on other sites More sharing options...
misterp Posted May 7, 2007 Report Share Posted May 7, 2007 There are reports of limited-slip additives varnishing the differential clutch pack; according to a GM TSB on the subject the G80 is specifically designed to be used with synthetic GL-5. Mr. P. Quote Link to comment Share on other sites More sharing options...
haulin79 Posted May 7, 2007 Report Share Posted May 7, 2007 All else being equal, a 75w-90 is better than 80w-90. Quote Link to comment Share on other sites More sharing options...
detjoe Posted May 7, 2007 Author Report Share Posted May 7, 2007 The book says to use 80W-90, but the only thing I can find in the stores is synthetic 75W-90 and it works well if not better. Don't add any other additives. Mr. P. All else being equal, a 75w-90 is better than 80w-90. thanks guys thats what I want to hear. Now if my sorry ass places have 5 qts...usually they have two I have considered getting some royal purplue if I do it with my buddy and his TBSS...oh well I did do my 8th oil change since I had the SS yesterday...I am kind of obsessive and keep all my oil change data on the filter so I can keep track... Quote Link to comment Share on other sites More sharing options...
misterp Posted May 7, 2007 Report Share Posted May 7, 2007 thanks guys thats what I want to hear. Now if my sorry ass places have 5 qts...usually they have two I have considered getting some royal purplue if I do it with my buddy and his TBSS...oh well I did do my 8th oil change since I had the SS yesterday...I am kind of obsessive and keep all my oil change data on the filter so I can keep track... Yeah it seems every auto parts store I've gone to is always out of the stuff. I would also consider a premium synthetic gear lube, because it's going to be in there so long that IMO the cost can be justified. Quote Link to comment Share on other sites More sharing options...
Quik Posted May 7, 2007 Report Share Posted May 7, 2007 the tbss diff is different then the SSS diff. the Tbss diff doesnt need additive, the SSS needs additive TBSS is a true posi where as the SSS is a locking style diff that uses clutches on the one side aka....your fine Josh relax!!! Quote Link to comment Share on other sites More sharing options...
misterp Posted May 7, 2007 Report Share Posted May 7, 2007 the tbss diff is different then the SSS diff. the Tbss diff doesnt need additive, the SSS needs additive TBSS is a true posi where as the SSS is a locking style diff that uses clutches on the one side aka....your fine Josh relax!!! Zippy provided the TSB on that here: http://www.SilveradoSS.com/forums/index.ph...st&p=200487 But, I have added LSD friction modifier additive in my rear axle and have had no problems. Mr. P. Quote Link to comment Share on other sites More sharing options...
Krambo Posted May 7, 2007 Report Share Posted May 7, 2007 I run NO ADDITIVE in my diffs. Just Mobile 1 75-90. Quote Link to comment Share on other sites More sharing options...
detjoe Posted May 8, 2007 Author Report Share Posted May 8, 2007 I called it, autozone only had 2 qts...oh well got the front done and not a moment too soon. The fisrt pic is what it looked like when I pulled it out, I am @ 28K miles The second pic is when I felt the grime. The third was after I cleaned it and put it in and pulled it back out to see how much more I could get...I was surprized at how much was still in there, after the third time it was pretty clean. The fourth pic just shows the clean plug for referance...yea there was a ton of junk on that plug! Quote Link to comment Share on other sites More sharing options...
Bad Bowtie Posted May 8, 2007 Report Share Posted May 8, 2007 (edited) HOLY CRAP DUDE!! Edited May 8, 2007 by Bad Bowtie (see edit history) Quote Link to comment Share on other sites More sharing options...
johnkoestler Posted May 16, 2007 Report Share Posted May 16, 2007 Dude, If your only at 28k and that is what your diff looked like I better check mine. Quote Link to comment Share on other sites More sharing options...
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