I saw Mobil 1 synthetic gear oil 75-140 on sale today (local auto parts store going out of buisiness). Has anyone used this heavy of a gear oil. Label says it meets GL-5 requirements??


Thanks

Some folks do as that weight was in the manual for heavy towing.

I dont know about using that gear oil or not, I dont see why not, especially if it is in the manual like the hound dog OOOOOOOOOOOWWWWW says. But Ive got a question. After drainging the rear differential, where do you refill from?

The drain plug is on the bottom of the diff and the fill plug is about halfway up on the diff cover.

It may be okay to use, but Mobil 1 does not meet the GM spec listed for the rear lube. Edited by: Roegs

That is true, it doesn't have the GM spec 9986115. Someone posted a lengthy correspondance with Eaton, the manufacturer of the rear diff, and IIRC they, Eaton, stated nothing about the GM number, only GL-5. I can't remember if that was posted here or at the other page as it was quite a while back.

The problem with talking about what the axle manufacturer says is okay, is that they are not the ones issuing the warranty...http://www.dieselplace.com/forum/smileys/Confused.gif


I was all set to use the Mobil for mine, and then I read that post about the GM spec. I think I'm going to try and locate the AC Delco stuff since it was a chunk cheaper.

Yep, that's very true. My 36,000 warranty is LONG gone, but then again I've been running either Amsoil or Mobil1 in the diffs since the breakin lube was dumped @ 500 mi. It boils down to what you're comfortable with. You're comfortable with your warranty with the Juice and I was comfortable with the warranty with non-GM spec gear lube in the diffs along with other things. BTW, the ACD stuff always costs more about 20/quart vs about 6/quart. Edited by: Hound

I just got around to dumping both diff's this weekend at 7,300 miles, rear was very dirty, front not so much but there was a pile of junk on the magnet at the tip of the plug! Mobil1 in both! I had to add almost 2 qts of fluid to the rear right after I picked it up (all I had on the shelf was Mobil 1) so I figure I'll just keep using it!

Why is the AC Delco so much more money?


It has to meet the GL-5....what ever that means.

NoWake,


According to a post from I believe one of our Canadian members, there is another GM approved lube labeled AC Delco. It meets the GM spec as well as the GL-5 and cost less than Grape Juice.


Do a search for it, if you don't find it I'll see if I can come up with it later today.Edited by: Zeeb

Unless your doing really heavy towing in real warm weather, I don't think you'll realize any benefit from the 75W-140. In fact, some people have noted mileage decrease due to the higher viscosity of the 75W-140. Could have heat build up too.


For you guys worrying about the Grape Juice and GM warranty, GM does not recognize Allison's Transynd spec and extended drain intervals either.


However, my SM does and he's the guy who supports me for warranty work.

http://www.dieselplace.com/forum/smileys/Geek.gif


Wondering about anyone using Amsoil series 2000 75W-90 gear lube, anyone using it? Thanks

Your AC Delco part # for grape juice is 89021678


I paid $16.95 per liter in Canadian $'s from the dealer


Thats about $2.99 US$'s http://www.dieselplace.com/forum/smileys/HiHi.gif





Rob

Anything wrong with "Royal Purple Max-Gear"? It's synthetic, meets GL-5, only about $8 a quart, and best of all its Purple!!

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My Chevy dealer wanted $25,00 a bottle for the grape juice. I got syn. Valvoline 75W- 90W for a lot less money. I got over 15 K since changed and no problems.


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Mobil 1 Synthetic Gear Lubricant LS 75W-90 meets the most severe API Service MT-1 and GL-5 EP gear oil service classification.

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_Synthetic_Gear_Lubricant_LS_75W-90.asp

I had to pay $33 before tax per quart for the GM grape juice.

I bought the GM stuff 75W-90 at the dealer when I changed over to the Mag-Hytech cover. Paid $12.06 CDN/946ml (1 US Quart). That's approx $9.25US/quart. It's GM part number 12378261. Not sure if that's what you guys are using in the States but service manager says it's the GM approved grape juice for HD rear axles (GL5 rating). That price was about 3 months ago. I'm really surprised at the price difference if in fact it's the same lube.http://www.dieselplace.com/forum/smileys/Shocked.gif

I wonder what's better. The 2 qts of grape juice that came in the rear end from the factory or the 4 qts of Mobil 1 I run http://www.dieselplace.com/forum/smileys/Clown.gif ????

"I got syn. Valvoline 75W- 90W for a lot less money."


I also have the synthetic Valvoline in the pumpkins. Just a good feeling to dump the contaminated stuff that came out. http://www.dieselplace.com/forum/smileys/Big Smile.gif

I got 2 qts of mobil 75w-90 synthetic today, those were the only two bottles they had left, sounds like a couple of you are using this stuff so im assuming its ok, but im wondering if i should just add some oil since it sounds like they are low to begin with or if i should drain it and refill, probly the latter? how much oil do these things hold?

I wouldn't mix them but that's just me. It's so easy to change and only costs around $7 a quart so I dont see the need to avoid a drain and refill. 4 qts rear 2 qts front. I always buy 7 just because it makes the change a little easier. I changed at 500 miles and 15k. Next will be at 50k and every 50k thereafter.

I'm reading a lot of you folks have only ~2 quarts in the rear differential from the factory. I just changed my rear diff'l fluid (~4,600 miles) and noticed the same thing!

I used 4 quarts of the GM "grape juice", purchased from DmaxalliTech for $22/qt. There was also a fair amount of crud on the drain plug magnet. The biggest piece about the size of a small finger-nail clipping.

HBruns

Thanks, I completely forgot that id be mixing them anyways.

It may be okay to use, but Mobil 1 does not meet the GM spec listed for the rear lube.
According to Mobil their synthetic is 100% compatible with the GM trucks, and meets all their specs.

Just a little story. Brother worked for an IH dealership and had set a irrigation engine. Crank seized on the new unit some time later. My brother told him it was probaly because of the filters and oil he used. To make a long story short the guy contacted the filter manufacturer. The big guys there talked to the big guys at IH. The big guys at IH called the local dealer manager and told them to shut up and warranty the engine. End of Story!!!!

I change my diff fluild at 3000 miles and that was with 500 miles of towing on it, I did not see much on the mag, the rear only had 2 1/2 qts in it and I replaced it 75-140 synthetic 3 3/4 qts GM grape juice, have not done the front one yet. didn't care about the price for the fluild, I look at it this way you spend 50,000 on a truck whats a 100 bucks for fluild LOL

I've been running Royel Purple for 50K now and it works for me. I am using the 75-140 because I pull a trailer alot of the time.

My initial switch was from grape juice to Mobil 1 75w/90. In anticipation of some heavy towing in the mountains next month I changed again yesterday to Redline Oil's 75w/140. When I first changed to Mobil I was very disturbed to find lots of grit and unpleasant bits crud on the plug and around the drain hole. The Mobil I drained out yesterday was black, but otherwise perfectly clean and had a lot more miles on it that the factory stuff.

TC

Don't believe in the BS GM is trying to sell us! As long the oil meets the API classification its OK and safe to use. That whats the API (classification) is for.

Whatever the manufacturer of the diff (Eaton) approves is good anyway. Thats NOT an ultra high performance engine but just a differential with locker! If it breaks down with the "wrong oil" its not worth a dime for me and I will put another real diff(s) in my pumpkin(s). Mobil 1 is definitely OK, the viscosity you use just really depends on the application, real heat needs real juice (140 weight) but no grape juice...