Clutch LSD Oil Change Interval
 

Thought I'd share my finding, it definitely was helpful to me, hope it will help fellow Z owners as well.

I have ATS metal LSD, clutch type, installed on my 2015 370Z. According to ATS instructions, any GL5 LSD oil will work but it has to be changed every 2-3k miles. I also called ATS to ask about change interval after events, I do autocross only now, they advised that I change it after every event.

In addition to the pain of changing LSD oil every other month, I have gone through the trial and error of trying LSD oils to find the best balance between longevity and noise (friction modifier additives). The first LSD oil I used was motul 90PA, which is mineral-based, first impression was excellent, made my LSD quiet as if it was carbon LSD. But it broke down rather quickly after 1200 miles and the LSD started making some noise (at low speeds, you know what I mean if you have a clutch LSD) and harsher engagements.

I then switch to 75W140 Royal Purple gear oil hoping that it has higher viscosity and it will make the LSD smoother. It was the exact opposite, extremely noisy and harsh engagements with that oil.

During that time, I changed my Evo 10 (which has 9k miles) LSD oil using OEM diaqueen 90 SAE LSD Oil. Searching the forums, lots of people swearing by that LSD oil compared to aftermarket ones. So I thought I'd give it a try. It is so far the best balance between noise, longevity and performance, especially since you can snatch a quart for $12 from MAP performance!

Now let's get to the oil analysis, I have Blackstone analysis of diaqueen 90 SAE virgin oil to measure at the additives, and then I sent another sample of the oil after two autocross events (not one as ATS advised). Blackstone technician probably thought I was crazy for changing the oil that frequently, especially since the oil was in pretty good shape. They advise that I try again after four events. Attached are both virgin and used oil for reference.

Next I will do three to four events on the LSD oil that I have right now, I will send another sample to Blackstone and will report back here.

changing LSD oil that frequently is not only cost prohibitive but it's also a pain in the ***. I do love my car and I like to service it, but with that much of service, it was becoming cumbersome as if I am caring for a special need Z. Excuse any typos as I'm posting this off my phone.

You should be good for 15k miles unless you overheat the diff fluid. In that case, you are changing it after ever event. What you need is a diff cooler. This will prevent the overheating. Contact MA-Motorsports. Talk with John.

Also install a diff temp gauge to see how high your diff temps are getting too.

Definitely love that oil cooler! But with an average 1 minutes per run on autocross, I will be shocked if I could boil the LSD oil. Going take my infrared thermometer to the next event and check the LSD cover temperature after each run. Thanks, Rusty!

When your lube temps get around 270F. It's starts to break down. This is the same for engine oil too. The higher the temp. The faster it breaks down. At 300F, it's cooked.

Which is why I sent the oil after two events to Blackstone, it seems that the oil wasn't cooked.

If you do canyon carving it will be an issue. On the east coast, The Dragon is hell on diff fluid temps.

Diff temps on the Dragon will get to 255F without a cooler.

The Dragon was the straw that broke the camel's back and why I got a MMA rear diff cooler.

Sent from my SM-G965U using Tapatalk

I was leaving a stinky trail behind me. LOL

Hey Rusty, the diff highest temp was 170F after Autocross lap, but it got to 230F after high-way driving for 1 hour (with 60-70F weather). I called MA-Motorspots john referred me to Brian who said that those numbers are not bad and I might not need a cooler. Thoughts?

If you are using a temp gun. You are not getting a true lube temp. You could tack on another 10 degrees maybe more inside the diff.

What you got for doing a auto-x isn't bad. Street driving is getting up there. If you had a diff temp gauge. You would have a better idea of what's going on.

What gets me. Even the stock diff temps get up there close to cooking the lube. :shakes head: