Gear Oil- 80w-90 vs 75w90

I used the CarQuest brand in mine from Advance. 80w-90


https://shop.advanceautoparts.com/p...oil-1-qt-780-32/7070233-P?searchTerm=Gear+oil

 

I run regular Valvoline 80w90 in the diffs and tcase. You can get gallon jugs at AutoZone.

 

Synthetic oil runs cooler, and that is why I pay for it. It can easily drop the temperature 20 to 25 degrees in the rear diff under high load conditions. That should translate into longer gear and seal life.

 

I have been running 75 90 in front tranny tcase and rear in all my trucks no issues. The 93 has 385k on it n the 08 has 200k my old 05 dodge had 275k.

 

How do you know the temp of the differential, scan gauge?

 

Very hard to find this one, atleast at the walmarts near me. Ended up buying Super Tech GL-5 80w-90 at $13.28 a gallon.

 

I use this oil but mine is a semi synthetic blend GL5, this bottle says full synthetic on it, other than that it works as well as the higher priced lubes(as far as I can tell) for 1/4 of the cost of boutique high priced stuff, just change it at 30k miles and good to go.

 

I have a dedicated temperature probe in the rear diff, and I have done hundreds of measurements with a laser to understand what is happening in there. I did this because I use my truck for towing and other trucky things, and I have always been nervous about the 8" ring and pinion in these trucks. I did a lot of testing with dino and synthetic oil, so what I'm saying is first hand, not theory. Now of course, Toyota has gone down in engine size, but offers a bigger R&P.

 

Just did gearbox and rr diff last wknd. Since auto parts places have no more than 3 of the same jug of gear oil I bought 3 Lucas HD 80-90w, 3 Valvoline 80-90w & 1 Lucas Oil Stabilizer. I ending up mixing 1 1/2 qts Lucas 80-90w, 1/2 qt Lucas oil stabilizer & 1 qt of the Valvoline in diff and gearbox. Stuff there had been in there at least 50k miles and still looked super fresh but didn't feel super fresh. It was time for fresh. It is never that cold down here to worry about 75-90 vs 80-90w. All oil I used exceeded GL-4 and GL-5 specs.

 

the one you like the most

 

Interesting, thx

 

cus it wont hurt and its cheap!

 

I researched some since I asked you this question. It appears you're correct. It seems like it's not a real LS additive they put in it and it's kind of a misleading label if you're truly wanting LS additive. I just ordered 10 bottles from your link for less than $100 delivered. I need it for my front diff, rear diff, t-case and wife's BMW so this saved me some coin. Thanks!

 

Its a true LS additive in it, you would have no problems using it on the mechanical LSD of the 08- trucks. But the additive itself will not harm a NON mechanical LS diff.

 

I read a bunch of people having issues and having to add extra LS additive. Grinding, clicking and/or moaning sounds that went away after either changing to a different gear oil or adding an LS additive. Moot point for me but thought I'd mention it.

 

I run 75w140 Redline GL5 in both my front and rear diffs, 75w85 Redline GL5 in the Trans case and MT-90 GL4 in my MT. Pretty fucking expensive to do every 30k...and likely overkill as my fluids look really fresh every time I swap them out but I'm looking to hold onto this truck for a while and would rather put the $$$ up front in PM rather than breaking down.

 

I hear ya, I own a 13' as well. I only have 25K on my truck though, but its almost 5 years old. So it's probably overkill for me to even change it now ( though I do go on the beach in the summer). How tight were the bolts on the transfer and differential when you first changed yours?

 

Tcase wasn't too bad. Front diff drain and fill were both very very very tight

 

Breaker bar type tight?

 

in all of my families driving counting many different makes and models, only twice was there an issue with a diff and that was my 88 toy 4x4 that had a bad pinion bearing at the factory that groaned since 5k miles and my brothers 68 nova after racing it getting low 11s in the 1/4