80/90 is correct.however you can't beat 75w-140 synthetic for a better lube and better fuel economy,especially in cold weather.should you decide on the synthetic (at least mobil 1) then you wouldn't need the extra friction modifier.

 

Been using this for years, the ole girl loves it. (Admittedly what I have available is vastly different from the southern guys) I use Lucas brand in everything but my trans.
I don't haul anywhere near as heavy as some of these guys, but I push her hard, and force my LS to lock up going like 80 km/h (50mp/h) on forest service roads, or faster on the freeway with all the standing water we get up here on the Wet coast of Canada, she loves it. Don't skimp, you will pay for it later.

 

awesome. thanks!

 

Any 80/90 or 75/140 that has a LS after the numbers is reqired in a limited slip rear. if you have a LS rear it is just a spring loaded clutch pack in the spider gears that trys to limit the amount of movement of the spider set, thus the wheel with the least traction is less likely to spin excessively, the spring can be changed to decrease the slip in the clutch pack, it is the modifier that protects the clutch disks from damage. rtv black will work with syn oils, the 75/140 is a thiner oil at low temps and thicker when hot, this is to save gas on short trips and light loads, when heating is not a problem LS lubes will work fine in Open diff rear ends

 

75w-140 will not be thinner in cold than 80w-90.





Lucas is a complete fail. People use the Lucas Oil Stabilizer for no good reason even though it has ZERO additives and low flashpoint. All it does is dilute fully formulated oil and add gunky sludge and it sheers.

 

Um... it *does* work to keep a leaky engine alive, though.
I have a '93 block which I swapped into my '88 at one point while it was being rebuilt. Unfortunately, I tried to re-seal that motor before installing it, and put the main seals in /backwards/. So I was leaving a trail of oil behind me.
Had to take a 300 mile trip the next day and didn't have time to fix it, so I just added Lucas as the oil leaked out. I lost like 2 quarts of oil(pre-lucas) in 50 miles; after I ended up adding a gallon of lucas, I think I ended up adding a total of another quart or two during the whole 300 mile trip. And then 300 miles back a week later, and I probably added a bit more, but it still dropped the consumption by quite a bit.

It also has massive surface tension and will stay on surfaces for years.
Last time I pulled apart an engine that had Lucas in it, there was a nice, sticky layer of oil stuck to everything. It didn't all 'drain down' like plain oil does.

I didn't see any 'sludge', either. Just sticky(thick) oil, at least at the temperatures I was working at.

That being said, I'm sure it's exactly what it seems to be: 175 weight oil.
And, on anything that wasn't critically leaking, or having some other major issue, I'm not going to use it - there's no point.


Going back to the graph above, though... They weren't talking about the Oil Stabilizer at all.
I'm not sure what's going on there, whether they got a fluke or something, but it looks like the oil /starts out/ really high, and then after the test it was right in the range it is supposed to be for a 90wt oil. So, that means either Lucas added something that has to break down to become proper weight oil, or something... I don't get it quite.

 

Care to elaborate with some facts?

 

I just put Royal Purple in my rear end, according to this it is garbage ?