LSD gear oil? Help putting diff back together in a few hours.

[E30Rookie37]

So I went to my friendly neighborhood race shop to get what was supposed to be redline 75w90 but turns out they don't have redline but have Motul instead. Motul is apparently on par with or better then redline according to them. I was about to buy the motul 75w90 but the guy told me for the LSD I wanted the motul 75w140 and it already has the ls modifier in it. The product looks to be of very high quality but I'm just not sure about the 75w140's weight and I'm skeptical of It having the ls modifier in it.
They seemed very knowledgeable and had never heard anything about this oil so I just went with it. They also had a perfect 2002 in the display room that the owner raced which was encouraging as to
Their knowledge of BMW. What do you guys think?

[E30Rookie37]

Bump

[geezerman402]

No idea about Motul vs Redline as I only use Redline, but I believe LSD additive simply allows the clutches to slip a bit better and thus reduces whine. Nothing more than that.

(as I have read on a forum, anyway)

[///digitalme]

i heard that, that brand is better quality than redline... but only heard it from people that track their cars

[Jaxx_]

Motul is amazing and usually difficult to find. I would consider it better than redline.

[Emre]

the guy told me for the LSD I wanted the Motul 75w140 and it already has the ls modifier in it. The product looks to be of very high quality but I'm just not sure about the 75w140's weight and I'm skeptical of It having the ls modifier in it...What do you guys think?

That's the gear lube recommended by Diffsonline for their race diffs. Probably overkill for street use.

i heard that, that brand is better quality than redline

When it comes to transmission and LSD gear lubes, regularly flushing them with the correct formulation is significantly more important than brand. Remember, there are no filters to catch the junk, so fluid changes are the only way to flush out contaminants and keep wear to a minimum.

Having said that, I tend to stick with Red Line, Motul, and Amsoil. But I honestly don't think it makes a significant difference.

[E30Rookie37]

Alright based on what you guys have said I think I'm going to swap the Motul 75w140 out for the Motul 75w90 that they had there also and then adding the friction modifier.

[AndrewBird]

When it comes to transmission and LSD gear lubes, regularly flushing them with the correct formulation is significantly more important than brand. Remember, there are no filters to catch the junk, so fluid changes are the only way to flush out contaminants and keep wear to a minimum.

While all of that is true, you also have to realize because they are sealed units, contaminants can't get in, therefore the need to change the oil is far less then the need to change, say, engine oil. The "junk" you speak of doesn't really exist unless something bad happened and there are pieces of your diff floating around inside. Though I suppose the friction plates would wear down a bit over a long period and introduce some junk into the oil.

[F34R]

They are a speed shop for a reason, that oil is just fine and would not worry about using it. Only reason you want a lighter fluid is if you are tracking every weekend. You then would need to change the fluid much more often.

You can buy the Redline with it already in it also. And if you really want it just google search Redline 75W140 LSD fluid. I am using it myself from when I rebuilt my LSD last summer.

[Jaxx_]

Only reason you want a lighter fluid is if you are tracking every weekend.

wat

[E30Rookie37]

wat

Yeah this... What? You mean heavier oil is better for tracking your car? Regardless I went back to the speed shop today and they were pretty insistent on this being perfect for e30 lsd's so I think I'm going to go with it. Although I bought 75w90 today as well in case.

The owner of the shop is going to make a call to Motul for me to double check.

[Jaxx_]

Yeah this... What? You mean heavier oil is better for tracking your car? Regardless I went back to the speed shop today and they were pretty insistent on this being perfect for e30 lsd's so I think I'm going to go with it. Although I bought 75w90 today as well in case.

The owner of the shop is going to make a call to Motul for me to double check.

I would always take what a shop says with a grain of salt, but in this case they're right in saying it will work, but in the grand scheme of things, nothing is "perfect." At the end of the day they are trying to sell product, but I do think that Motul has quality fluids, and if it were available locally I would grab some.

I think 75-140 is great, usually when you get bumped into the higher weights it's like 85-140, instead of 75-90. I'd rather have an oil that can perform at higher temperatures than one that will net me a few extra hp. My reasoning is that I'd rather finish races than be first for one race. extreme argument, but I'd like equipment to last long than perform beyond it's means.

[AndrewBird]

Owners manual says to use 90 weight, but you won't notice a difference either way.

[kalib0y]

Royal purple 75/90

[TimR]

What ever on the oil, BG LSD II has resurected a couple diffs for me, I some areas you still have to get it from a dealer. In Biz. 40 years, got to be doing something right. Thier tranny add. is good too.