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noviceowner
02-20-2003, 15:13
There are oil manufacturers who describe this weight of their product has having a low cold weather pour point (-49F) or excellent cold temperature lubricating properties. Do you know what GM uses for this weight and if there is a website describing its properties? I will be towing a fifth wheel and am concerned about following the manual's guidelines to use 75w140 oil in the rear diff. instead of the 75w90 for non towing. As some of you have pointed out, using this in a cold climate such as mine in Maine may be a viscosity issue. Thanks for your help! smile.gif Wendy
03 2500HD CC SB D/A
MadDuraMax
02-20-2003, 15:32
Wendy,

The first number in the differential lube both being 75W, means that they both will have simular cold flowing properties. The last number (90 or 140) refers to the lubes viscosity when hot.

Not knowing the exact brand, dino -vs- synthetic etc. that you are using, but I would not expect to see you having any problems with either lube.

Mark
noviceowner
02-20-2003, 15:44
Hi Mark! I'm going to have it changed at the Chevy dealer and I believe they use syn but I don't know what brand. Your explanation of the weight designations and properties was very helpful. Thanks!
jbplock
02-22-2003, 05:50
Wendy,

Having the dealer change the Diff fluid will likely be expensive. They will probably use the GM "Grape Juice" which is about $28/quart. A friend took his Dmax to the dealer and he was charged $150.00 to do the change. If you wanted to save a few bucks there are good synthetic GL5 lubes that are much cheaper than the re-labeled (Texaco?) GM stuff. It's not hard to change because there is a drain plug (don't have to remove the cover). If you haven’t already done so, search the forum for Diff info. TxDoc posted some good info he got directly from Eaton.

smile.gif

[ 02-22-2003: Message edited by: jbplock ]</p>
1822
02-22-2003, 06:06
I am pretty sire the lube you want is Texaco SynStar 80w/140. I use this in my shop on lots of different equipment and it has performed well. It costs about $5.00 per quart. I also have it in both diffs of my 02 3500 with posi rear.